fixed type hint of hrandfield method

Signed-off-by: amirreza <amir.rsf1380@gmail.com>

Author: amirreza8002

valkey/commands/core.py

@@ -2153,7 +2153,7 @@ def pttl(self, name: KeyT) -> ResponseT:
 
     def hrandfield(
         self, key: str, count: int = None, withvalues: bool = False
-    ) -> ResponseT:
+    ) -> Union[bytes, List[bytes], None]:
         """
         Return a random field from the hash value stored at key.