Implemented nightly rebuild of Docker images

Author: merlinschumacher

.github/workflows/main.yml

@@ -1,10 +1,12 @@
 name: Push
 
 on:
+  schedule:
+    - cron: '*/15 0 * * *'
   push:
     branches: 
       - master
-
+  
 jobs:
   build:
     runs-on: ubuntu-latest