ci: add a new workflow to build and push experimental images

.github/workflows/experimental.yml

@@ -0,0 +1,36 @@
+name: Build & Push experimental images
+
+on:
+  schedule:
+    - cron: "0 0 1 * *"
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/[email protected]
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKER_USER }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Set up Docker Buildx
+        id: buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Build and push Docker images
+        run: |
+          BAKE_JSON="bakefiles/experimental.docker-bake.json" \
+          BAKE_GROUP="default" \
+          BAKE_OPTION=--push \
+          make bake-json-group