skip cleanup in ci to speed up tests

dokku

@@ -83,8 +83,10 @@ fi
 case "$1" in
   receive)
     APP="$2"; IMAGE=$(get_app_image_name $APP); IMAGE_SOURCE_TYPE="$3"; TMP_WORK_DIR="$4"
-    dokku_log_info1 "Cleaning up..."
-    docker_cleanup
+    if [[ -z "DOKKU_SKIP_CLEANUP" ]]; then
+      dokku_log_info1 "Cleaning up..."
+      docker_cleanup
+    fi
     dokku_log_info1 "Building $APP from $IMAGE_SOURCE_TYPE..."
     dokku build "$APP" "$IMAGE_SOURCE_TYPE" "$TMP_WORK_DIR"
     release_and_deploy "$APP"