fix enum check

Signed-off-by: Panos Vagenas <[email protected]>

Author: vagenas

docling_core/experimental/idoctags.py

@@ -116,7 +116,7 @@ def _serialize_meta_field(self, meta: BaseMeta, name: str) -> Optional[str]:
                 return None
             # elif tmp := str(field_val or ""):
             #     txt = tmp
-            elif name not in MetaFieldName:
+            elif name not in {v.value for v in MetaFieldName}:
                 txt = _wrap(text=str(field_val or ""), wrap_tag=name)
             return txt
         return None