Tag images correctly

Signed-off-by: Stephen Finucane <[email protected]>

.github/workflows/publish-image.yaml

@@ -2,10 +2,11 @@
 name: Publish container image
 on:
   push:
-  pull_request:
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
   cancel-in-progress: true
+env:
+  BRANCH: ${{ github.head_ref || github.ref_name }}
 jobs:
   push_to_registry:
     name: Push container image to GitHub Container Registry
@@ -21,8 +22,10 @@ jobs:
           registry: ghcr.io
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Generate tag name
+        run: echo "IMAGE_TAG=${BRANCH/\//-}" >> $GITHUB_ENV
       - name: Build and push container image
         uses: docker/build-push-action@v6
         with:
           push: true
-          tags: ghcr.io/${{ github.repository }}:latest
+          tags: ghcr.io/${{ github.repository }}:${{ env.IMAGE_TAG }}