ci: add flatpak build

Signed-off-by: 0xMRTT <0xMRTT@proton.me>

.github/workflows/build.yml

@@ -0,0 +1,36 @@
+name: Build
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+
+jobs:
+  flatpak:
+    name: Flatpak
+    runs-on: ubuntu-latest
+    container:
+      image: bilelmoussaoui/flatpak-github-actions:gnome-nightly
+      options: --privileged
+    strategy:
+      matrix:
+        arch: [x86_64, aarch64]
+      fail-fast: false
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Install dependencies
+        run: |
+          dnf -y install docker
+      - name: Set up QEMU
+        id: qemu
+        uses: docker/setup-qemu-action@v2.1.0
+        with:
+          platforms: arm64
+      - uses: flatpak/flatpak-github-actions/flatpak-builder@v5
+        with:
+          repository-name: gnome-nightly
+          bundle: bavarder.flatpak
+          manifest-path: build-aux/flatpak/com.github.Bavarder.Bavarder.json
+          cache-key: flatpak-builder-${{ github.sha }}
+          arch: ${{ matrix.arch }}