mypy

e48a0258 - Remove unnecessary --python-version 3.8 references from tests (#16850)

Remove unnecessary --python-version 3.8 references from tests (#16850) Remove the `--python-version 3.8` flag where it's used to indicate the min python version requirement. Mypy doesn't support running under Python 3.7 / the tests are only run for 3.8+.