Remove upper version bounds from black and mypy

[Vuizur]

Pull request title

• I read contributing guideline
• I didn't find a similar pull request already open.
• My PR is related to Spleeter only, not a derivative product (such as Webapplication, or GUI provided by others)

Description

This removes the upper bounds from the tools black and mypy. This upper bound caused poetry to install old versions of these libraries, which have the deprecated library typed_ast as a dependency. Trying to install this library on a system with a newer Python version (for example 3.10) causes the attempt to compile the wheel for typed_ast, which fails with an error message like this: python/typed_ast#126

This PR fixes this issue, as newer versions of black and mypy don't require typed_ast anymore.

How this patch was tested

• I implemented unit test whicn ran successfully using poetry run pytest tests/
• Code has been formatted using poetry run black spleeter
• Imports has been formatted using `poetry run isort spleeter``

Documentation link and external references

Please provide any info that may help us better understand your code.