fix: [vps] support 'docker compose' naming convention for finding mysql container

bin/vps

@@ -272,7 +272,11 @@ mailcow:install-backup() {
         return 1
     }
 
+    if docker compose >/dev/null 2>&1; then
+        MYSQL_CONTAINER=${MYSQL_CONTAINER:-mailcowdockerized-mysql-mailcow-1}
+    else
         MYSQL_CONTAINER=${MYSQL_CONTAINER:-mailcowdockerized_mysql-mailcow_1}
+    fi
     container_id=$(docker ps -f name="$MYSQL_CONTAINER" --format "{{.ID}}")
     if [ -z "$container_id" ]; then
         err "Couldn't find docker container named '$MYSQL_CONTAINER'."