Move GitHub Actions for ARM for separate file

- We will include these long running jobs only on special branches

.github/workflows/test-arm-container-images.yaml

@@ -0,0 +1,48 @@
+name: Test ARM Container Images
+
+on:
+  push:
+    branches:
+      - 'arm/**'
+  pull_request:
+    branches:
+      - 'arm/**'
+
+jobs:
+  test_images:
+    name: Test Latest Container Images
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        context:
+          - apache
+          - fpm-alpine
+          - fpm
+        platform:
+          - linux/arm64
+    steps:
+      - name: 'Check out the repo'
+        uses: actions/checkout@v3
+
+      - name: 'Set up QEMU'
+        uses: docker/setup-qemu-action@v2
+        with:
+          platforms: 'arm64,arm'
+
+      - name: 'Set up Docker Buildx'
+        uses: docker/setup-buildx-action@v2
+
+      - name: 'Build Container images'
+        uses: docker/build-push-action@v3
+        with:
+          context: 6.0/${{ matrix.context }}
+          push: false
+          load: true
+          tags: docker.io/martialblog/limesurvey:6-${{ matrix.context }}
+          platforms: ${{ matrix.platform }}
+
+      - name: 'Run Structure tests'
+        uses: plexsystems/container-structure-test-action@v0.2.0
+        with:
+          image: docker.io/martialblog/limesurvey:6-${{ matrix.context }}
+          config: tests/${{ matrix.context }}-tests.yaml

.github/workflows/test-latest-container-images.yaml

@@ -12,9 +12,6 @@ jobs:
           - apache
           - fpm-alpine
           - fpm
-        platform:
-          - linux/amd64
-          - linux/arm64
     steps:
       - name: 'Check out the repo'
         uses: actions/checkout@v3
@@ -34,7 +31,6 @@ jobs:
           push: false
           load: true
           tags: docker.io/martialblog/limesurvey:6-${{ matrix.context }}
-          platforms: ${{ matrix.platform }}
 
       - name: 'Run Structure tests'
         uses: plexsystems/container-structure-test-action@v0.2.0

CONTRIBUTING.md

@@ -59,3 +59,9 @@ make fpm-alpine-latest
 
 container-structure-test test --image  docker.io/martialblog/limesurvey:5-fpm --config tests/fpm-tests.yaml
 ```
+
+### ARM Platform
+
+Changes related to the ARM platform should use branches starting with the `arm/` prefix, this ensures the GitHub Actions are triggered.
+
+Background: ARM builds take a long time to finish on the GitHub Runners.