Remove some unneeded dependencies

[Swatinem]

This removes a bunch of dependencies which were only needed for forward compatibility across Python versions, as well as some very niche dependencies with well-established alternatives.

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This is extracted from #423, and ships a few improvements and blockers before fully switching to uv.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.79%. Comparing base (26f0db0) to head (3e5c971).
Report is 2 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #425 +/- ##
==========================================
- Coverage 90.23% 89.79% -0.45% 
==========================================
Files 389 324 -65 Lines 11802 9457 -2345 Branches 2063 1688 -375 ==========================================
- Hits 10650 8492 -2158 + Misses 1052 901 -151 + Partials 100 64 -36 

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