See Changelog.

• Make includes/excludes arguments for .dict(), ._iter(), ..., immutable, #1404 by @AlexECX
• Always use a field's real name with includes/excludes in model._iter(), regardless of by_alias, #1397 by @AlexECX
• Update constr regex example to include start and end lines, #1396 by @lmcnearney
• Confirm that shallow model.copy() does make a shallow copy of attributes, #1383 by @samuelcolvin
• Renaming model_name argument of main.create_model() to __model_name to allow using model_name as a field name, #1367 by @kittipatv
• Replace raising of exception to silent passing for non-Var attributes in mypy plugin, #1345 by @b0g3r
• Remove typing_extensions dependency for python 3.8, #1342 by @prettywood
• Make SecretStr and SecretBytes initialization idempotent, #1330 by @atheuz
• document making secret types dumpable using the json method, #1328 by @atheuz
• Move all testing and build to github actions, add windows and macos binaries, thank you @StephenBrown2 for much help, #1326 by @samuelcolvin
• fix card number length check in PaymentCardNumber, PaymentCardBrand now inherits from str, #1317 by @samuelcolvin
• Have BaseModel inherit from Representation to make mypy happy when overriding __str__, #1310 by @FuegoFro
• Allow None as input to all optional list fields, #1307 by @prettywood
• Add datetime field to default_factory example, #1301 by @StephenBrown2
• Allow subclasses of known types to be encoded with superclass encoder, #1291 by @StephenBrown2
• Exclude exported fields from all elements of a list/tuple of submodels/dicts with '__all__', #1286 by @masalim2
• Add pydantic.color.Color objects as available input for Color fields, #1258 by @leosussan
• In examples, type nullable fields as Optional, so that these are valid mypy annotations, #1248 by @kokes
• Make pattern_validator() accept pre-compiled Pattern objects. Fix str_validator() return type to str, #1237 by @adamgreg
• Document how to manage Generics and inheritance, #1229 by @esadruhn
• update_forward_refs() method of BaseModel now copies __dict__ of class module instead of modyfying it, #1228 by @paul-ilyin
• Support instance methods and class methods with @validate_arguments, #1222 by @samuelcolvin
• Add default_factory argument to Field to create a dynamic default value by passing a zero-argument callable, #1210 by @prettywood
• add support for NewType of List, Optional, etc, #1207 by @Kazy
• fix mypy signature for root_validator, #1192 by @samuelcolvin
• Fixed parsing of nested 'custom root type' models, #1190 by @Shados
• Add validate_arguments function decorator which checks the arguments to a function matches type annotations, #1179 by @samuelcolvin
• Add __signature__ to models, #1034 by @MrMrRobat
• Refactor ._iter() method, 10x speed boost for dict(model), #1017 by @MrMrRobat