fix: remove deprecated compose version tag

examples/yourls/docker-compose.yml

@@ -1,5 +1,3 @@
-version: '3.1'
-
 services:
 
   yourls:
@@ -34,6 +32,8 @@ services:
     image: mysql:latest
     container_name: yourls-db
     restart: unless-stopped
+    expose:
+      - 3306
     environment:
       MYSQL_DATABASE: yourls
       MYSQL_USER: yourls