update license metadata per PEP639

[2bndy5]

resolves #105

drops support for python v3.7 and v3.8 (see rationale below #107 (comment))

[2bndy5]

I had to revert the merge from #106 because it requires an updated version of setuptools. Meaning we cannot build distributions for Python v3.7 and v3.8 with these changes.

• Support for PEP639 (for which this patch is aimed) was added in setuptools v77.0.0
• Support for Python v3.8 was dropped in setuptools v75.3.2
• Support for Python v3.7 was dropped in setuptools v68.1.0

I have to investigate a bit more. My concern is for the majority of people that don't update their RPi machines to use newer versions of python.

Tip

See also Python Life Cycle

Caution

I'm ok with dropping support for Python v3.7 because it has been dead for over a year. But Python v3.8 was only recently discontinued in Oct 2024.

On the other hand

We could simply stop building binary distributions for Python v3.8 and v3.7. This would force users of said versions to build from our source distribution (which currently includes a copy of pybind11 v2.13.6).

FWIW, PyBind11 will be dropping support for v3.7 in the next release. So we will still be pinned to PyBind11 v2.13.6 (latest as of this writing) until we also drop support for these older versions of Python.

[2bndy5]

Considering

1. Bump pypa/cibuildwheel from 2.23.0 to 2.23.3 in the github-actions group #111 (comment)
2. pybind11 v3 also dropped support for python v3.7 (& PyPy v3.8 and v3.9)

Its getting harder to keep distributing wheels for deprecated versions of python prior v3.9.
Right now, I feel like we're in a sweet spot where wheels for python v3.13 to v3.7 can still be built with our current build dependency tree. 😬

I'll move forward on this when python v3.14 starts having stable releases (in Oct 2025).