Also check the existence of _fields in addition to__annotations__ for NamedTuple. (#36337)

* Check the existence of _fields instead of __annotations__ for NamedTuple.

* Still need to check the existence of __annotations__.

* Format the changes

Author: yilei

sdks/python/apache_beam/typehints/native_type_compatibility.py

@@ -164,7 +164,7 @@ def _match_is_exactly_sequence(user_type):
 def match_is_named_tuple(user_type):
   return (
       _safe_issubclass(user_type, typing.Tuple) and
-      hasattr(user_type, '__annotations__'))
+      hasattr(user_type, '__annotations__') and hasattr(user_type, '_fields'))
 
 
 def _match_is_optional(user_type):