python3-packaging: upgrade 26.2 -> 26.3

python3-packaging: upgrade 26.2 -> 26.3

- Add a public VersionRange API and SpecifierSet.to_range(),
  representing the versions a specifier set accepts as an interval set
  that supports intersection, union, difference, complement, set
  relations, membership tests, and filtering.
  VersionRange.to_specifier_set() converts a range back to a
  SpecifierSet where a PEP 440 form exists.
- PEP 808: accept Metadata-Version: 2.6.
- Add a limit argument to parse_tag() for compressed tag sets.
- Add a prefer_sdist_predicate argument to Pylock.select() to prefer
  source distributions over wheels for selected packages.
- Add pure_python_tags() to generate the pure-Python tags for a Python
  version without touching the running platform.
- Add SpecifierSet.is_subset(), SpecifierSet.is_superset(), and
  SpecifierSet.is_disjoint(), which compare the versions two specifier
  sets accept.
- Drop support for Python 3.8; packaging now requires Python 3.9 or
  later.
- Prefer native linux_* platform tags over manylinux and musllinux tags
  on Linux. - Add a musl/Alpine test job and make the test suite pass on
  musl.

The tests now work on musl so don't skip the manylinux tests.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>