chore: Make _delete_cache_fields protected

Author: last-partizan

modeltranslation/translator.py

@@ -419,7 +419,7 @@ def patch_refresh_from_db(model: type[Model]) -> None:
     model.refresh_from_db = build_refresh_from_db(model.refresh_from_db)
 
 
-def delete_cache_fields(model: type[Model]) -> None:
+def _delete_cache_fields(model: type[Model]) -> None:
     opts = model._meta
     cached_attrs = (
         "_field_cache",
@@ -583,7 +583,7 @@ def _register_single_model(self, model: type[Model], opts: TranslationOptions) -
 
         # Add translation fields to the model.
         if model._meta.proxy:
-            delete_cache_fields(model)
+            _delete_cache_fields(model)
         else:
             add_translation_fields(model, opts)
 
@@ -595,7 +595,7 @@ def _register_single_model(self, model: type[Model], opts: TranslationOptions) -
         )
 
         for related_obj in related:
-            delete_cache_fields(related_obj.model)
+            _delete_cache_fields(related_obj.model)
 
         # Set MultilingualManager
         add_manager(model)