add github action

wip...

.github/workflows/main.yml

@@ -0,0 +1,36 @@
+# This is a basic workflow to help you get started with Actions
+
+name: Build yunohost rpi image
+
+# Controls when the workflow will run
+on:
+  # Triggers the workflow on push or pull request events but only for the "yunohost-buster" branch
+  push:
+    branches: [ "yunohost-bullseye" ]
+  pull_request:
+    branches: [ "yunohost-bullseye" ]
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+# A workflow run is made up of one or more jobs that can run sequentially or in parallel
+jobs:
+  # This workflow contains a single job called "build"
+  build:
+    # The type of runner that the job will run on
+    runs-on: ubuntu-20.04
+
+    # Steps represent a sequence of tasks that will be executed as part of the job
+    steps:
+      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
+      - uses: actions/checkout@v3
+
+      # Runs a set of commands using the runners shell
+      - name: Run a multi-line script
+        run: |
+          apt update
+          apt-get -y install coreutils quilt parted qemu-user-static debootstrap zerofree zip dosfstools libarchive-tools libcap2-bin grep rsync xz-utils file git curl bc qemu-utils kpartx gpg pigz
+          curl -fsSL https://get.docker.com -o get-docker.sh
+          sh get-docker.sh
+          ./build-docker.sh
+