fix minor code smells

ormar/fields/foreign_key.py

@@ -72,8 +72,6 @@ class UniqueColumns(UniqueConstraint):
     Used to avoid importing anything from sqlalchemy by user.
     """
 
-    pass
-
 
 @dataclass
 class ForeignKeyConstraint:

ormar/fields/model_fields.py

@@ -112,7 +112,6 @@ class ModelFieldFactory:
         :param kwargs: all params passed during construction
         :type kwargs: Any
         """
-        pass
 
 
 class String(ModelFieldFactory, str):

ormar/models/helpers/models.py

@@ -79,5 +79,4 @@ def validate_related_names_in_relations(
                     f"default/empty name: '{new_model.get_name() + 's'}'"
                     f"\nTip: provide different related_name for FK and/or M2M fields"
                 )
-            else:
-                previous_related_names.append(field.related_name)
+            previous_related_names.append(field.related_name)