make _SchemaMeta hashable for ruff pre-commit test

Author: tikuma-lsuhsc

tests/test_integration_autodoc_type_aliases.py

@@ -38,6 +38,7 @@ def dec(val: T) -> T:
 
 
 class _SchemaMeta(type):
+    def __hash__(cls): ...
     def __eq__(cls, other: object) -> bool:
         return True