Drop Python 3.8

[NeilGirdhar]

Python 3.8 is dead, and the faulty license gives a warning in Python 3.14:

  /Users/neil/.cache/uv/builds-v0/.tmpssvJcI/lib/python3.14/site-packages/setuptools/config/_apply_pyprojecttoml.py:82: SetuptoolsDeprecationWarning: `project.license` as a TOML
  table is deprecated

          Please use a simple string containing a SPDX expression for `project.license`. You can also use `project.license-files`. (Both options available on setuptools>=77.0.0).

          By 2026-Feb-18, you need to update your project and remove deprecated calls
          or your builds will no longer be supported.

          See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for details.
          ********************************************************************************

[NeilGirdhar]

Might as well drop 3.9 in 2 weeks too.

[methane]

3.8 had been dropped in main branch already.
I have not yet decided whether to remove Python 3.9 support in the next release.

[NeilGirdhar]

@methane Did you update pyproject as per this PR somewhere? I don't see these changes in the main branch.

msgpack-python/pyproject.toml

Line 11 in d9873da

license = {text="Apache 2.0"}

[methane]

No. I just dropped from ci. It will be updated in next release.

[NeilGirdhar]

Sounds good, thank you