Update network for gotify

gotify/docker-compose.yml

@@ -8,5 +8,11 @@ services:
     volumes:
       - ${APPDATA_PATH}/gotify/config:/app/data
     ports:
-      - "${PORT}:80"
+      - ${PORT}:80
+    networks:
+      - frontend
     restart: unless-stopped
+
+networks:
+  frontend:
+    external: true