Openfisca-core

Bug fix

- [Web API] Handle a period mismatch error
- Period mismatch error was not being handled by the API
- Since it's caused by the user, a 400 (bad request error) is to be expected
- However, since it was not being handled, a 500 (internal server error) was being given instead

Bug fix

- Properly check for date validity in parameters.
- Date validity was being checked only partially, allowing parameters with illegal dates such as "2015-13-32".
- The changes introduced fix this error and prevent the user when a parameter date is illegal.

Technical changes

- Update dependencies (_as in 35.3.7_).
- Extend NumPy compatibility to v1.20 to support M1 processors.

- Make NumPy's type-checking compatible with 1.17.0+
- NumPy introduced their `typing` module since 1.20.0
- Previous type hints relying on `annotations` will henceforward no longer work
- This changes ensure that type hints are always legal for the last four minor NumPy versions

Bug fix

- Drop latest NumPy supported version to 1.18.x
- OpenFisca relies on MyPy for optional duck & static type checking
- When libraries do not implement their own types, MyPy provides stubs, or type sheds
- Thanks to `__future__.annotations`, those stubs or type sheds are casted to `typing.Any`
- Since 1.20.x, NumPy now provides their own type definitions
- The introduction of NumPy 1.20.x in 990 caused one major problem:
- It is general practice to do not import at runtime modules only used for typing purposes, thanks to the `typing.TYPE_CHEKING` variable
- The new `numpy.typing` module was being imported at runtime, rendering OpenFisca unusable to all users depending on previous versions of NumPy (1.20.x-)
- These changes revert 990 and solve 1009 and 1012

_Note: this version has been unpublished due to an issue introduced by NumPy upgrade. Please use 34.3.8 or a more recent version._

Technical changes

- Update dependencies.
- Extend NumPy compatibility to v1.20 to support M1 processors.

Technical changes

- In web_api tests, extract `test_client` to a fixture reusable by all the tests in the test suite.
- To mitigate possible performance issues, by default the fixture is initialised once per test module.
- This follows the same approach as [997](https://github.com/openfisca/openfisca-core/pull/997)