build: drop python 3.8

[tlambert03]

are you ok with dropping python 3.8 @cmalinmayor? it's the only thing keeping #65 from passing, and python 3.8 is officially end of life

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.85%. Comparing base (0fdfae7) to head (f240078).
Report is 10 commits behind head on main.

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HEAD has 2 uploads less than BASE

Flag	BASE (0fdfae7)	HEAD (f240078)
	12	10

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #66       +/-   ##
===========================================
- Coverage   75.72%   60.85%   -14.88%     
===========================================
  Files          17       19        +2     
  Lines         828     1152      +324     
  Branches      154      311      +157     
===========================================
+ Hits          627      701       +74     
- Misses        136      428      +292     
+ Partials       65       23       -42     

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[tlambert03]

important notes for anyone paying attention to this PR: in addition to dropping python 3.8, this pr pins setuptools to <72. lots changed in that version which broke the build here, so this pin is introduced both in our build-system.requires, as well as the dev extra (which is used on ci)

[tlambert03]

another note: i tried to support python 3.13 here, but it appears that there is no version of gurobi that yet supports 3.13 (and until #14 is resolved, we must have gurobi to build