Fix test warnings

[Incred]

Fix RuntimeWarning during testing:

tests/test_regressions.py::test_serializer_foreign_key_default_value_handling                                                                                                                                        
  /home/incred/dev/drf-spectacular/venv/lib64/python3.11/site-packages/django/db/models/base.py:364: RuntimeWarning: Model 'tests.m10' was already registered. Reloading models is not advised as it can lead to inco
nsistencies, most notably with related models.                                                                                                                                                                       
    new_class._meta.apps.register_model(new_class._meta.app_label, new_class)                                                                                                                                        
                                                                                                                                                                                                                     
tests/test_regressions.py::test_serializer_foreign_key_default_value_handling
  /home/incred/dev/drf-spectacular/venv/lib64/python3.11/site-packages/django/db/models/base.py:364: RuntimeWarning: Model 'tests.m11' was already registered. Reloading models is not advised as it can lead to inco
nsistencies, most notably with related models.
    new_class._meta.apps.register_model(new_class._meta.app_label, new_class)

Renamed those model's classes using new names to avoid warnings.

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (06a39ad) 98.62% compared to head (3f8ed7f) 98.62%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #959   +/-   ##
=======================================
  Coverage   98.62%   98.62%           
=======================================
  Files          68       68           
  Lines        8216     8216           
=======================================
  Hits         8103     8103           
  Misses        113      113           

Impacted Files	Coverage Δ
tests/test_regressions.py	99.94% <100.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

[tfranzel]

🤦 ..... thanks @Incred!