fix: return copy of schema without 'definitions' key

Instead of delete key 'definitions' from schema, bc schema was "cached" and if you try to load swagger twice, you got "no definitions" exception

aiohttp_pydantic/oas/view.py

@@ -55,9 +55,8 @@ class _OASResponseBuilder:
         if 'definitions' in schema:
             for k, v in schema['definitions'].items():
                 self._definitions[k] = v
-            del schema['definitions']
 
-        return schema
+        return {i:schema[i] for i in schema if i!='definitions'}
 
     def _handle_pydantic_base_model(self, obj):
         if is_pydantic_base_model(obj):