Update gotify/server Docker tag to v3.1.0

Author: renovate[bot]

apps/gotify/3.0.0/docker-compose.yml

@@ -1,6 +1,6 @@
 services:
   gotify:
-    image: "gotify/server:3.0.0"
+    image: "gotify/server:3.1.0"
     container_name: ${CONTAINER_NAME}
     restart: always
     networks: