set separate runner for arm64 build

.gitea/workflows/docker-builder.yml

@@ -8,6 +8,7 @@ on:
 
 jobs:
   build:
+    name: Build amd64
     runs-on: ubuntu-latest
 
     steps:
@@ -33,11 +34,6 @@ jobs:
             -u ${{ secrets.REGISTRY_USER }} \
             --password-stdin
                          
-      - name: Setup Docker Buildx
-        run: |
-          docker buildx create --name multiarch --use || docker buildx use multiarch
-          docker buildx inspect --bootstrap
-              
       - name: Build & push amd64
         run: |
           docker build \
@@ -47,11 +43,36 @@ jobs:
             -t git.pi-farm.de/pi-farm/docker-baseimage-alpine:${VERSION} .
           docker push git.pi-farm.de/pi-farm/docker-baseimage-alpine:${VERSION}
   
+  build:
+    name: Build arm64
+    runs-on: arm64-builder
 
-      - name: Build & push arm64 with buildx builder
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set image tag from branch
         run: |
-          docker buildx build \
+          # hole den Branch-Namen über Git
-            --platform linux/arm64 \
+          VERSION=$(git rev-parse --abbrev-ref HEAD)
+
+          if [ -z "$VERSION" ]; then
+            echo "ERROR: could not determine branch name"
+            exit 1
+          fi
+          echo "VERSION=$VERSION" >> $GITEA_ENV
+          echo "BUILD_DATE=$(date -u +%Y-%m-%dT%H:%M:%SZ)" >> $GITEA_ENV
+
+      - name: Login to registry
+        run: |
+          echo "${{ secrets.REGISTRY_PASSWORD }}" | docker login \
+            git.pi-farm.de \
+            -u ${{ secrets.REGISTRY_USER }} \
+            --password-stdin
+                         
+      - name: Build & push arm64
+        run: |
+          docker build \
             -f Dockerfile.aarch64 \
             --build-arg BUILD_DATE=${BUILD_DATE} \
             --build-arg VERSION=${VERSION} \