What's Changed
* tweak typing by PrettyWood in https://github.com/pydantic/pydantic-core/pull/271
* add `outer_location` argument to `ValidatorCallable` by samuelcolvin in https://github.com/pydantic/pydantic-core/pull/277
* Generator type by samuelcolvin in https://github.com/pydantic/pydantic-core/pull/276
* `is_instance` JSON support by samuelcolvin in https://github.com/pydantic/pydantic-core/pull/278
* fix `JsonType` copy by samuelcolvin in https://github.com/pydantic/pydantic-core/pull/279
* validator title and optionally omit context by samuelcolvin in https://github.com/pydantic/pydantic-core/pull/283
* Improve errors by sanders41 in https://github.com/pydantic/pydantic-core/pull/270
* support `deque` input to list, tuple etc., change how lengths are validated by samuelcolvin in https://github.com/pydantic/pydantic-core/pull/275
* adding `PydanticOmit` exception by samuelcolvin in https://github.com/pydantic/pydantic-core/pull/282
* unique error kinds by samuelcolvin in https://github.com/pydantic/pydantic-core/pull/285
* Custom error kind by samuelcolvin in https://github.com/pydantic/pydantic-core/pull/284
New Contributors
* sanders41 made their first contribution in https://github.com/pydantic/pydantic-core/pull/270
**Full Changelog**: https://github.com/pydantic/pydantic-core/compare/v0.3.1...v0.4.0