speedup docker builds with a cache

.github/workflows/docker_prod.yml

@@ -17,6 +17,10 @@ on:
 jobs:
   docker:
     runs-on: ubuntu-latest
+    timeout-minutes: 30
+    permissions:
+      contents: read
+      packages: write
     steps:
       - name: Checkout
         uses: actions/checkout@v3
@@ -47,12 +51,6 @@ jobs:
             type=ref,event=pr
             type=raw,value=latest,enable=${{ github.ref == 'refs/heads/main' || startsWith(github.ref, 'refs/tags/') }}
 
-
-
-
-
-
-          
       - name: Login to DockerHub
         if: github.event_name != 'pull_request'
         uses: docker/login-action@v2
@@ -68,3 +66,5 @@ jobs:
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=registry,ref=ghcr.io/jokob-sk/pi.alert:buildcache
+          cache-to: type=registry,ref=ghcr.io/jokob-sk/pi.alert:buildcache,mode=max