Add a build workflow

.github/workflows/build.yml

@@ -0,0 +1,32 @@
+name: Build and push to build branch.
+
+on:
+  push:
+    branches: [build-test]
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
+        with:
+          ref: trunk
+
+      - name: Setup
+        uses: WordPress/wporg-repo-tools/.github/actions/setup@trunk
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Add all the files
+        run: |
+          git add * --force
+
+      - name: Commit and push
+        uses: actions-js/push@a52398fac807b0c1e5f1492c969b477c8560a0ba # 1.3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          branch: build
+          force: true
+          message: 'Build: ${{ github.sha }}'