Fix invalid return type annotation (redis#3480)

Author: birthdaysgift

redis/connection.py

@@ -672,7 +672,7 @@ def pack_commands(self, commands):
             output.append(SYM_EMPTY.join(pieces))
         return output
 
-    def get_protocol(self) -> int or str:
+    def get_protocol(self) -> Union[int, str]:
         return self.protocol
 
     @property