python: Use ‘not in’ for more negated membership tests.

Fixes “E713 Test for membership should be `not in`” found by ruff (now
that I’ve fixed it not to ignore scripts lacking a .py extension).

Signed-off-by: Anders Kaseorg <anders@zulip.com>

scripts/nagios/check-rabbitmq-consumers

@@ -19,7 +19,7 @@ states = {
     3: "UNKNOWN",
 }
 
-if "USER" in os.environ and not os.environ["USER"] in ["root", "rabbitmq"]:
+if "USER" in os.environ and os.environ["USER"] not in ["root", "rabbitmq"]:
     print("This script must be run as the root or rabbitmq user")