Hack: patch setuptools < 77 to support modern licenses

[gpotter2]

This PR is a hack to support old setuptools with the new license format.

• fixes SetuptoolsDeprecationWarnings: "project.license as a TOML table is deprecated" and "License classifiers are deprecated" #4849
• replaces Fix PEP 639 license warnings & drop Python 3.7/3.8 #4924

See pypa/setuptools#4903 for more details. This should allow us to keep 3.7 support after all. @evverx what do you think?

As dumb as it is, Python 3.7 is still Scapy's biggest usage, by far.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.15%. Comparing base (5c3fe1c) to head (6fa4552).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4931      +/-   ##
==========================================
- Coverage   80.15%   80.15%   -0.01%     
==========================================
  Files         370      370              
  Lines       91759    91759              
==========================================
- Hits        73553    73552       -1     
- Misses      18206    18207       +1     

see 5 files with indirect coverage changes

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[guedou]

Shall we get the exception and print it to ease debugging if needed?

[guedou]

LGTM. I made a minor comment.

[evverx]

@gpotter2 I have to admit I'm not sure what to do. Looking at https://pypistats.org/packages/scapy it seems Python3.7 jumped from ~17% to ~55% in October 2025 and even reached ~70% at some point and I don't even know how it can be explained. Personally I think it should be fine to keep emitting warnings with newer toolchains and cut off Python3.7/3.8 when the setuptools deadline gets close enough (or when it becomes too burdensome to support Python3.7/3.8 overall). Places with specific legacy requirements can always patch scapy. For example https://src.fedoraproject.org/rpms/scapy/blob/rawhide/f/scapy-2.7.0-rhel9.patch downgrades setuptools even more.