test(ci): build docker image in github workflow

.github/workflows/build-docker.yml

@@ -0,0 +1,33 @@
+name: Build Docker image
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+
+env:
+  DOCKER_IMAGE_NAME: joinmarket-clientserver
+  DOCKER_IMAGE_TAG: test
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Build
+        uses: docker/build-push-action@v6
+        env:
+          SOURCE_DATE_EPOCH: 0
+        with:
+          load: true
+          push: false
+          tags: ${{ env.DOCKER_IMAGE_NAME }}:${{ env.DOCKER_IMAGE_TAG }}