Upgrade packaging to 24.0

[zangruochen]

Upgrade packaging to 24.0.

Removed LegacyVersion and LegacySpecifiler related code as packaging has removed LegacyVersion and LegacySpecifiler.

pypa/packaging#407

[notatallshaw]

Are you familiar with the existing PR that has been attempting to do this #12300?

Also note any PR that does this must at every step of collecting packages skip versions and specifiers that now fail to parse, otherwise during backtracking, metadata and link collection pip will error out incorrectly, (some good example installs to try would be pytz, nltk, apache-airflow[all], and pandas, and these need to tries on pypi, and downlodaing all the packages and using --find-links against a url and a file system).

And finally, and I'm sure pip maintainers are well aware of this, but while pip desperately needs to upgrade packaging for a whole host of reasons it will be a disruptive breaking changing, uv has had to support many non-standard version and specifiers to be compatible with the Python packaging ecosystem, even though pip has been warning now for many releases that legacy versions and specifiers will fail in an upcoming release. Not sure what can be done about that, but it's been eye opening watching uv have to add support for lots of non-standard versions and specifiers.