ci: build aarch64 flatpak images

Author: geigi

.github/workflows/flatpak.yml

@@ -7,14 +7,30 @@ jobs:
     runs-on: ubuntu-latest
 
     container:
-      image: bilelmoussaoui/flatpak-github-actions:gnome-40
+      image: bilelmoussaoui/flatpak-github-actions:gnome-41
       options: --privileged
 
+    strategy:
+      matrix:
+        arch: [x86_64, aarch64]
+      # Don't fail the whole workflow if one architecture fails
+      fail-fast: false
     steps:
     - uses: actions/checkout@v2
 
+    - name: Set up QEMU
+      id: qemu
+      uses: docker/setup-qemu-action@v1
+      with:
+        platforms: arm64
+    
+    - name: Install deps
+      run: |
+        dnf -y install docker
+
     - uses: bilelmoussaoui/flatpak-github-actions/flatpak-builder@v4
       with:
         bundle: Cozy.flatpak
         manifest-path: com.github.geigi.cozy.json
         cache-key: "flatpak-builder-${{ github.sha }}"
+        arch: ${{ matrix.arch }}