chore: drop Python 3.11 support

[feanil]

Summary

• Drop Python 3.11 support: remove from CI test matrix, tox envlist, and package classifiers
• Regenerate pinned requirements using Python 3.12
• Bump version to 1.0.0 — dropping Python support is a breaking change, so this is a major version bump

Context

Python 3.11 is being dropped across the Open edX ecosystem as part of the move
to standardize on Python 3.12. See the tracking issue for the full list of repos:
openedx/public-engineering#499

Test plan

• CI passes with Python 3.12 only

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.44%. Comparing base (db4ed32) to head (47375b2).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #120   +/-   ##
=======================================
  Coverage   88.44%   88.44%           
=======================================
  Files           6        6           
  Lines         476      476           
=======================================
  Hits          421      421           
  Misses         55       55           

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