build: Dependabot config and build workflow

.github/dependabot.yml

@@ -0,0 +1,19 @@
+version: 2
+updates:
+  # Maintain dependencies for GitHub Actions
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    groups:
+      github-actions:
+        patterns:
+          - "*"
+  - package-ecosystem: "docker"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    groups:
+      docker:
+        patterns:
+          - "*"

.github/workflows/buildimage.yml

@@ -0,0 +1,37 @@
+name: BuildImage
+
+on:
+  workflow_dispatch:
+
+permissions:  # added using https://github.com/step-security/secure-workflows
+  contents: read
+
+jobs:
+  build_multi_arch_images:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@68827325e0b33c7199eb31dd4e31fbe9023e06e3 # v3.0.0
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@f95db51fddba0c2d1ec667646a06c2ce06100226 # v3.0.0
+
+      - name: Login to DockerHub
+        uses: docker/login-action@343f7c4344506bcbf9b4de18042ae17996df046d # v3.0.0
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push Multi Arch buildimage
+        id: docker_build
+        uses: docker/build-push-action@4a13e500e55cf31b7a5d59a38ab2040ab0f42f56 # v5.1.0
+        with:
+          file: ./Dockerfile
+          push: true
+          provenance: false
+          tags: |
+            atsigncompany/cbuildimage:latest
+            atsigncompany/cbuildimage:GHA_${{ github.run_number }}
+          platforms: |
+            linux/amd64
+            linux/arm64/v8