feat: nextcloud backup script

nextcloud/docker-compose.yml

@@ -5,11 +5,12 @@ services:
     command: --transaction-isolation=READ-COMMITTED --binlog-format=ROW
     volumes:
       - ./db:/var/lib/mysql
+      - ./backup:/backup
     env_file: 
-      - env
+      - .env
 
   app:
-    image: nextcloud
+    image: nextcloud:stable
     restart: always
     ports:
       - 50000:80
@@ -18,4 +19,4 @@ services:
     volumes:
       - ./nextcloud:/var/www/html
     env_file: 
-      - env
+      - .env