ci: new tag format on pr (#45)

Reviewed-on: https://git.mgrote.net///container-images/httpd/pulls/45
Co-authored-by: Michael Grote <michael.grote@posteo.de>
Co-committed-by: Michael Grote <michael.grote@posteo.de>

.gitea/workflows/build.yaml

@@ -1,4 +1,6 @@
 name: "lint, build and push"
+# https://docs.docker.com/build/ci/github-actions/manage-tags-labels/
+# Variables: https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/store-information-in-variables#default-environment-variables + https://forgejo.org/docs/latest/user/actions/#env-1
 on:
   schedule:
     - cron: "32 17 * * SUN"
@@ -6,8 +8,6 @@ on:
     branches: [ master ]
   pull_request:
 
-# Variables: https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/store-information-in-variables#default-environment-variables + https://forgejo.org/docs/latest/user/actions/#env-1
-
 jobs:
   lint:
     steps:
@@ -41,11 +41,21 @@ jobs:
             Status: ${{ job.status }}
             Source: ${{ github.head_ref }}
 
-
   build:
     needs: [gitleaks, hadolint] # shellcheck
     steps:
-      - uses: https://github.com/actions/checkout@v4
+      - name: Checkout code
+        uses: actions/checkout@v4
+      - name: Extract repository name
+        id: name
+        run: |
+          echo REPO_NAME=$(echo ${GITHUB_REPOSITORY} | awk -F"/" '{print $2}') >> $GITHUB_OUTPUT
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: |
+            registry.mgrote.net/${{ steps.name.outputs.REPO_NAME }}
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
 #      - name: Login to Docker Hub
@@ -53,21 +63,13 @@ jobs:
 #        with:
 #          username: ${{ secrets.DOCKERHUB_USERNAME }}
 #          password: ${{ secrets.DOCKERHUB_TOKEN }}
-      - name: Extract repository name
-        id: meta
-        run: |
-          echo REPO_NAME=$(echo ${GITHUB_REPOSITORY} | awk -F"/" '{print $2}') >> $GITHUB_OUTPUT
-      - name: Extract branch name
-        shell: bash
-        run: echo "REPO_BRANCH=${GITHUB_REF_NAME}" >> $GITHUB_OUTPUT
-        id: extract_branch
       - name: Build and push Docker image
         uses: https://github.com/docker/build-push-action@v6
         with:
           context: .
           file: ./Dockerfile
           push: true
-          tags: "registry.mgrote.net/${{ steps.meta.outputs.REPO_NAME }}:latest,registry.mgrote.net/${{ steps.meta.outputs.REPO_NAME }}:${{ steps.extract_branch.outputs.REPO_BRANCH }}"
+          tags: ${{ steps.meta.outputs.tags }}
       - name: Send notification
         uses: dawidd6/action-send-mail@v3
         if: failure()