Add build on pull request

.github/workflows/build.yml

@@ -0,0 +1,37 @@
+name: Docker Build
+
+on: pull_request
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  build:
+    name: Docker Build and Push
+    if: contains(github.event.pull_request.labels.*.name, 'documentation') != true
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+        with:
+          ref: ${{ github.ref }}
+          clean: true
+          fetch-depth: 0
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v3
+        with:
+          context: docker
+          push: true
+          tags: ghcr.io/${{ github.repository }}/vmpooler:pr${{ github.event.pull_request.number }}-${{ github.event.pull_request.head.sha }}