ruff can automatically detect this [1] now that it is defined in
pyproject.toml. mypy defaults to the version of Python used to run mypy
[2][3] so we need to keep its configuration around a while longer.

We also fix the 'project.authors' definition while we're here.

[1] https://docs.astral.sh/ruff/settings/#target-version
[2] https://mypy.readthedocs.io/en/stable/config_file.html#confval-python_version
[3] https://github.com/python/mypy/issues/19349



Change-Id: I1feaa80c2e11bce951ae0ab99c6f1f4b00faadb8
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>