Bump djangorestframework from 3.14.0 to 3.15.1

Bumps djangorestframework from 3.14.0 to 3.15.1.

Commits

• 3285916 Version 3.15.1 (#9339)
• eb361d2 SearchFilter.get_search_terms returns list. (#9338)
• 400b4c5 Revert "Fix NamespaceVersioning ignoring DEFAULT_VERSION on non-None namespac...
• 4ef3aaf Revert #9030 (#9333)
• 4f10c4e Revert "Fix Respect can_read_model permission in DjangoModelPermissions (#8...
• a4d5807 Revert "feat: Add some changes to ValidationError to support django style vad...
• da78a14 Revert "Re-prefetch related objects after updating (#8043)" (#9327)
• 0e4ed81 Revert "feat: Add some changes to ValidationError to support django style vad...
• 56a5b35 Add drf-sendables to third-party-packages.md (#9261)
• d7c8dcf Revert PR that adds autocomplete_fields to TokenAdmin, as this break some use...
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