feat: support strawberry 0.199.0+

[bellini666]

strawberry 0.199.0 changed the way generic type vars are handled to support the new generic syntax in Python 3.12.

This release adjusts our usage of generic type vars to match the new behaviour.

Fix #325

[codecov-commenter]

Codecov Report

Patch coverage: 83.33% and no project coverage change.

Comparison is base (eafbffc) 87.90% compared to head (4dfbb23) 87.90%.

❗ Current head 4dfbb23 differs from pull request most recent head 9da65d0. Consider uploading reports for the commit 9da65d0 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #326   +/-   ##
=======================================
  Coverage   87.90%   87.90%           
=======================================
  Files          33       33           
  Lines        2944     2944           
=======================================
  Hits         2588     2588           
  Misses        356      356           

Files Changed	Coverage Δ
strawberry_django/utils/inspect.py	79.48% <0.00%> (ø)
strawberry_django/fields/base.py	95.91% <100.00%> (ø)
strawberry_django/optimizer.py	89.63% <100.00%> (ø)

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[patrick91]

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