fix workflow part IV

Author: HenriWahl

.github/workflows/build-release-latest.yml

@@ -5,16 +5,27 @@ on:
     branches: '*'
 
 env:
-  cr_image: ghcr.io/${{ github.repository }}/build
+  # ERROR: failed to build: invalid tag "ghcr.io/HenriWahl/checkmk-agent-plugin-yum/build:build-image": repository name must be lowercase
+  # this is the penalty for using uppercase letters in repository names...
+  cr_image: ghcr.io/henriwahl/checkmk-agent-plugin-yum/build:${{ github.run_id }}
 
 jobs:
   build-image:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+      # docker login is needed for pushing the test image
+      - uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      # somehow weird way to get the hash over the requirements to be aware if they changed
+      - id: get_hash
+        run: echo "HASH=$(ls -l | md5sum ) | cut -d\  -f1)" >> $GITHUB_OUTPUT
       # build container image for package creation
-      - run: docker pull ${{ env.cr_image }}:${{ github.job }} || docker build -t ${{ env.cr_image }}:${{ github.job }} -f dockerfiles/checkmk/Dockerfile .
-      - run: docker push ${{ env.cr_image }}:${{ github.job }}
+      - run: docker pull ${{ env.cr_image }}:${{ steps.get_hash.outputs.HASH }} || docker build -t ${{ env.cr_image }}:${{ steps.get_hash.outputs.HASH }} -f dockerfiles/checkmk/Dockerfile .
+      - run: docker push ${{ env.cr_image }}:${{ steps.get_hash.outputs.HASH }}
 
 #  build-package:
 #    runs-on: ubuntu-latest