add release workflow for cross-building on debian bullseye

.github/workflows/cross-bullseye-arm64.yml

@@ -0,0 +1,37 @@
+name: Release Debian/Bullseye (crossbuild/arm64)
+
+on:
+  workflow_dispatch:
+
+jobs:
+  build:
+    permissions:
+      contents: write
+    runs-on: ubuntu-22.04
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v3
+
+    - name: Set up QEMU
+      uses: docker/setup-qemu-action@v2
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v2
+
+    - name: Build packages
+      run: |
+        if [ "${RUNNER_DEBUG}" = "1" ]; then
+          docker buildx build -o packages --build-arg buildoptions="cross debug" --build-arg baseimage=debian:bullseye-slim --platform linux/amd64 -f Dockerfile .
+        else
+          docker buildx build -o packages --build-arg buildoptions="cross" --build-arg baseimage=debian:bullseye-slim --platform linux/amd64 -f Dockerfile .
+        fi
+        echo "DEB_VERSION=$(dpkg --info packages/proxmox-backup-server_*.deb | sed -n '/Version/ s/[^:]\+: //p')" >> $GITHUB_ENV
+        echo "DEB_VERSION_UPSTREAM=$(dpkg --info packages/proxmox-backup-server_*.deb | sed -n '/Version/ s/[^:]\+: \([0-9.]\+\)-[0-9]/\1/p')" >> $GITHUB_ENV
+    - name: Release packages
+      uses: ncipollo/release-action@v1
+      with:
+        artifacts: "packages/*.deb"
+        bodyFile: "PREBUILD.md"
+        tag:  ${{ env.DEB_VERSION }}
+        name: Version ${{ env.DEB_VERSION }} (Debian/Bullseye)
+        draft: true