Changelog (https://github.com/symfony/symfony/compare/v6.3.3...v6.3.4)

• bug #51475 [Serializer] Fix union of enum denormalization (@mtarld)
• bug #51474 [Serializer] Fix wrong InvalidArgumentException thrown (@mtarld)
• bug #51494 Fixed attachment base64 content string in MailerSendApiTransport (@pavelwitassek)
• bug #51350 [Security] Prevent creating session in stateless firewalls (@Seb33300)
• bug #51104 [Security] Fix loading user from UserBadge (@guillaumesmo)
• bug #51473 [VarDumper] Fix managing collapse state in CliDumper (@nicolas-grekas)
• bug #51369 [Serializer] Fix deserializing object collection properties (@X-Coder264)
• bug #51399 [Serializer] Fix deserializing of nested snake_case attributes using CamelCaseToSnakeCaseNameConverter (@Victor-Truhanovich)
• bug #51456 [Serializer] Fix serialized name with groups during denormalization (@mtarld)
• bug #51445 [Security] FormLoginAuthenticator: fail for non-string password (@dmaicher)
• bug #51424 [HttpFoundation] Fix base URI detection on IIS with UrlRewriteModule (@derrabus)
• bug #51396 [HttpKernel] Fix missing Request in RequestStack for StreamedResponse (Ismail Turan)
• bug #51378 [Console] avoid multiple new line when message already ends with a new line in section output (@joelwurtz)
• bug #51336 [Notifier] [Pushover] Fix invalid method call + improve exception message (@ahmedghanem00)
• bug #51345 [AssetMapper] Fixing bug where a circular exception could be thrown while making error message (@weaverryan)
• bug #48840 [Validator] Dump Valid constraints on debug command (@macintoshplus)
• bug #51223 [Console] Fix linewraps in OutputFormatter (@maxbeckers)
• bug #51307 [DependencyInjection] fix dump xml with array/object/enum default value (@Jean-Beru)
• bug #51355 [Console] fix section output when multiples section with max height (@joelwurtz)
• bug #51359 [Security] Fix error with lock_factory in login_throttling (@BaptisteContreras)
• bug #51326 [FrameworkBundle] Fix xsd for handle-all-throwables (@Jean-Beru)
• bug #51328 [Messenger] Always return bool from messenger amqp connection nack (@Danielss89)
• bug #51295 [Mailer] update Brevo SMTP host (@bastien-wink)
• bug #51301 [FrameworkBundle] add missing default-doctrine-dbal-provider cache pool attribute to XSD (@xabbuh)
• bug #51296 [Process] Fix silencing wait when using a sigchild-enabled binary (@nicolas-grekas)
• bug #51251 [DependencyInjection] Do not add return in LazyClosure when return type of closure is void (@ruudk)
• bug #51219 [DependencyInjection][HttpKernel] Fix using #[AutowireCallable] with controller arguments (@HypeMC)
• bug #51201 [Workflow] fix MermaidDumper when place contains special char (@lyrixx)
• bug #49195 [Crawler] Fix regression where cdata nodes will return empty string (@NanoSector)
• bug #51061 [DoctrineBridge] Bugfix - Allow to remove LazyLoaded listeners by object (@VincentLanglet)
• bug #51190 [Clock] load function only if not loaded before (@xabbuh)

[PR] https://github.com/symfony/symfony/pull/51496