Convert the value to int type only if it exists in CLIENT INFO

Currently, client info will try to convert the set of keys to the int type
without checking if it exists or not. For example, both `argv-mem` and `tot-mem`
are introduced in 6.2, and force converting an non-existent value might
cause an exception in older version. To keep the compatibility with the older/newer
Redis server, we could just convert it only if the key exists.

Author: git-hulk

redis/_parsers/helpers.py

@@ -676,7 +676,8 @@ def parse_client_info(value):
         "omem",
         "tot-mem",
     }:
-        client_info[int_key] = int(client_info[int_key])
+        if int_key in client_info:
+            client_info[int_key] = int(client_info[int_key])
     return client_info