* configure isort to add the future annotations import
* apply the new isort setting
* remove type ignores for new mypy (#13539)
https://pypi.org/project/mypy/0.981/
* another
* streamable: Merge `strictdataclass` into `Streamable` class
* tests: Test not supported streamable types
* streamable: Reorder decorators
* streamable: Simplify streamable decorator and force correct usage/syntax
* streamable: Just move some stuff around in the file
* streamable: Improve syntax error messages
* mypy: Drop `type_checking.py` and `test_type_checking.py` from exclusion
* streamable: Use cached fields instead of `__annotations__`
This is now possible after merging `__post_init__` into `Streamable`
* Introduce `DefinitionError` as `StreamableError`
* `/t` -> ` `