.github: Add workflow for extension deploy

.github/workflows/deploy.yml

@@ -0,0 +1,20 @@
+name: Deploy BlueOS Extension Image
+
+on:
+  push:
+  # Run manually
+  workflow_dispatch:
+  # NOTE: caches may be removed if not run weekly
+  #  -> may be worth scheduling for every 6 days
+
+jobs:
+  deploy-docker-image:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Deploy BlueOS Extension
+        uses: BlueOS-community/[email protected]
+        with:
+          docker-username: ${{ secrets.DOCKER_USERNAME }}
+          docker-password: ${{ secrets.DOCKER_PASSWORD }}
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          image-name: 'cellphone-modem-manager'