switch to actions v2 format

.github/workflows/ci.yaml

@@ -35,12 +35,19 @@ jobs:
   containerise:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - name: Set up QEMU
+      uses: docker/setup-qemu-action@v1
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v1
     - name: Log into GitHub Container Registry
       run: echo "${{ secrets.REGISTRY_ACCESS_TOKEN }}" | docker login https://ghcr.io -u ${{ github.actor }} --password-stdin
-    - name: Build the container image
-      run: |
-        LATEST_TAG=ghcr.io/meeb/$IMAGE_NAME:latest
-        docker buildx create --name builder
-        docker buildx use builder
-        docker buildx build --platform linux/amd64 --tag $IMAGE_NAME --push .
+    - name: Build and push
+      uses: docker/build-push-action@v2
+      with:
+        context: .
+        file: ./Dockerfile
+        platforms: linux/amd64
+        push: true
+        tags: ghcr.io/meeb/$IMAGE_NAME:latest
+        cache-from: type=registry,ref=ghcr.io/meeb/$IMAGE_NAME:latest
+        cache-to: type=inline