[Compose] Rollback watchdog to 1.96

Due to https://github.com/nagios-plugins/nagios-plugins/pull/649 which cause the Certificate Check to fail.

docker-compose.yml

@@ -447,7 +447,7 @@ services:
         - /lib/modules:/lib/modules:ro
 
     watchdog-mailcow:
-      image: mailcow/watchdog:1.97
+      image: mailcow/watchdog:1.96
       dns:
         - ${IPV4_NETWORK:-172.22.1}.254
       tmpfs: