Remove assert statement from non-test files

Author: deepsource-autofix[bot]

openapi_python_client/openapi_parser/properties.py

@@ -295,7 +295,8 @@ def values_from_list(l: List[str]) -> Dict[str, str]:
                 key = value.upper()
             else:
                 key = f"VALUE_{i}"
-            assert key not in output, f"Duplicate key {key} in Enum"
+            if key in output:
+                raise AssertionError(f"Duplicate key {key} in Enum")
             output[key] = value
 
         return output