[Rspamd] Update to 3.4 (fix of 3.3 Bug)

docker-compose.yml

@@ -76,7 +76,7 @@ services:
             - clamd
 
     rspamd-mailcow:
-      image: mailcow/rspamd:1.90
+      image: mailcow/rspamd:1.91
       stop_grace_period: 30s
       depends_on:
         - dovecot-mailcow