chore(internal): fix lint error on Python 3.14

Author: stainless-app[bot]

src/llama_stack_client/_utils/_compat.py

@@ -32,7 +32,7 @@ def is_union(tp: Optional[Type[Any]]) -> bool:
     else:
         import types
 
-        return tp is Union or tp is types.UnionType
+        return tp is Union or tp is types.UnionType  # type: ignore[comparison-overlap]
 
 
 def is_typeddict(tp: Type[Any]) -> bool: