See #4419 for feedback and discussion, docs are live at pydantic-docs.helpmanual.io.

• Refactor the whole pydantic dataclass decorator to really act like its standard lib equivalent. It hence keeps __eq__, __hash__, ... and makes comparison with its non-validated version possible. It also fixes usage of frozen dataclasses in fields and usage of default_factory in nested dataclasses. The support of Config.extra has been added. Finally, config customization directly via a dict is now possible, #2557 by @PrettyWood
  
  BREAKING CHANGES:
  • The compiled boolean (whether pydantic is compiled with cython) has been moved from main.py to version.py
  • Now that Config.extra is supported, dataclass ignores by default extra arguments (like BaseModel)
• Fix PEP487 __set_name__ protocol in BaseModel for PrivateAttrs, #4407 by @tlambert03
• Allow for custom parsing of environment variables via parse_env_var in Config, #4406 by @acmiyaguchi
• Rename master to main, #4405 by @hramezani
• Fix StrictStr does not raise ValidationError when max_length is present in Field, #4388 by @hramezani
• Make SecretStr and SecretBytes hashable, #4387 by @chbndrhnns
• Fix StrictBytes does not raise ValidationError when max_length is present in Field, #4380 by @JeanArhancet
• Add support for bare type, #4375 by @hramezani
• Support Python 3.11, including binaries for 3.11 in PyPI, #4374 by @samuelcolvin
• Add support for re.Pattern, #4366 by @hramezani
• Fix __post_init_post_parse__ is incorrectly passed keyword arguments when no __post_init__ is defined, #4361 by @hramezani
• Fix implicitly importing ForwardRef and Callable from pydantic.typing instead of typing and also expose MappingIntStrAny, #4358 by @aminalaee
• remove Any types from the dataclass decorator so it can be used with the disallow_any_expr mypy option, #4356 by @DetachHead
• moved repo to pydantic/pydantic, #4348 by @yezz123
• fix "extra fields not permitted" error when dataclass with Extra.forbid is validated multiple times, #4343 by @detachhead
• Add Python 3.9 and 3.10 examples to docs, #4339 by @Bobronium
• Discriminated union models now use oneOf instead of anyOf when generating OpenAPI schema definitions, #4335 by @MaxwellPayne
• Allow type checkers to infer inner type of Json type. Json[list[str]] will be now inferred as list[str], Json[Any] should be used instead of plain Json. Runtime behaviour is not changed, #4332 by @Bobronium
• Allow empty string aliases by using a alias is not None check, rather than bool(alias), #4253 by @sergeytsaplin
• Update ForwardRefs in Field.outer_type_, #4249 by @JacobHayes
• The use of __dataclass_transform__ has been replaced by typing_extensions.dataclass_transform, which is the preferred way to mark pydantic models as a dataclass under PEP 681, #4241 by @multimeric
• Use parent model's Config when validating nested NamedTuple fields, #4219 by @synek
• Update BaseModel.construct to work with aliased Fields, #4192 by @kylebamos
• Catch certain raised errors in smart_deepcopy and revert to deepcopy if so, #4184 by @coneybeare
• Add Config.anystr_upper and to_upper kwarg to constr and conbytes, #4165 by @satheler
• Fix JSON schema for set and frozenset when they include default values, #4155 by @aminalaee
• Teach the mypy plugin that methods decorated by @validator are classmethods, #4102 by @DMRobertson
• Improve mypy plugin's ability to detect required fields, #4086 by @richardxia
• Support fields of type Type[] in schema, #4051 by @aminalaee
• Add default value in JSON Schema when const=True, #4031 by @aminalaee
• Adds reserved word check to signature generation logic, #4011 by @strue36
• Fix Json strategy failure for the complex nested field, #4005 by @sergiosim
• Add JSON-compatible float constraint allow_inf_nan, #3994 by @tiangolo
• Remove undefined behaviour when env_prefix had characters in common with env_nested_delimiter, #3975 by @arsenron
• Support generics model with create_model, #3945 by @hot123s
• allow submodels to overwrite extra field info, #3934 by @PrettyWood
• Document and test structural pattern matching (PEP 636) on BaseModel, #3920 by @irgolic
• Fix incorrect deserialization of python timedelta object to ISO 8601 for negative time deltas. Minus was serialized in incorrect place ("P-1DT23H59M59.888735S" instead of correct "-P1DT23H59M59.888735S"), #3899 by @07pepa
• Fix validation of discriminated union fields with an alias when passing a model instance, #3846 by @chornsby
• Add a CockroachDsn type to validate CockroachDB connection strings. The type supports the following schemes: cockroachdb, cockroachdb+psycopg2 and cockroachdb+asyncpg, #3839 by @blubber
• Fix MyPy plugin to not override pre-existing __init__ method in models, #3824 by @patrick91
• Fix mypy version checking, #3783 by @KotlinIsland
• support overwriting dunder attributes of BaseModel instances, #3777 by @PrettyWood
• Added ConstrainedDate and condate, #3740 by @hottwaj
• Support kw_only in dataclasses, #3670 by @detachhead
• Add comparison method for Color class, #3646 by @aminalaee
• Drop support for python3.6, associated cleanup, #3605 by @samuelcolvin
• created new function to_lower_camel() for "non pascal case" camel case, #3463 by @schlerp
• Add checks to default and default_factory arguments in Mypy plugin, #3430 by @klaa97
• fix mangling of inspect.signature for BaseModel, #3413 by @fix-inspect-signature
• Adds the SecretField abstract class so that all the current and future secret fields like SecretStr and SecretBytes will derive from it, #3409 by @expobrain
• Support multi hosts validation in PostgresDsn, #3337 by @rglsk
• Fix parsing of very small numeric timedelta values, #3315 by @samuelcolvin
• Update SecretsSettingsSource to respect config.case_sensitive, #3273 by @JeanArhancet
• Add MongoDB network data source name (DSN) schema, #3229 by @snosratiershad
• Add support for multiple dotenv files, #3222 by @rekyungmin
• Raise an explicit ConfigError when multiple fields are incorrectly set for a single validator, #3215 by @SunsetOrange
• Allow ellipsis on Fields inside Annotated for TypedDicts required, #3133 by @ezegomez
• Catch overflow errors in int_validator, #3112 by @ojii
• Adds a __rich_repr__ method to Representation class which enables pretty printing with Rich, #3099 by @willmcgugan
• Add percent encoding in AnyUrl and descendent types, #3061 by @FaresAhmedb
• validate_arguments decorator now supports alias, #3019 by @MAD-py
• Avoid __dict__ and __weakref__ attributes in AnyUrl and IP address fields, #2890 by @nuno-andre
• Add ability to use Final in a field type annotation, #2766 by @uriyyo
• Update requirement to typing_extensions>=4.1.0 to guarantee dataclass_transform is available, #4424 by @commonism
• Add Explosion and AWS to main sponsors, #4413 by @samuelcolvin
• Update documentation for copy_on_model_validation to reflect recent changes, #4369 by @samuelcolvin
• Runtime warning if __slots__ is passed to create_model, __slots__ is then ignored, #4432 by @samuelcolvin
• Add type hints to BaseSettings.Config to avoid mypy errors, also correct mypy version compatibility notice in docs, #4450 by @samuelcolvin

Full Changelog: https://github.com/pydantic/pydantic/compare/v1.9.0...v1.10.0