ci: Enable slashes in ref name as found in PRs

Author: colluca

.github/workflows/ci.yml

@@ -18,7 +18,20 @@ jobs:
     if: >
       github.event_name != 'pull_request' ||
       github.event.pull_request.head.repo.full_name != github.repository
+    # Export Docker image name used by dependent jobs
+    outputs:
+      image_name: ${{ steps.image_name.outputs.image_name }}
     steps:
+      - name: Define Docker image name
+        id: image_name
+        # To satisfy Docker tag naming requirements, we replace all slashes
+        # in the ref name with dashes.
+        run: |
+          SANITIZED_REF_NAME="${GITHUB_REF_NAME//\//-}"
+          echo "Sanitized GITHUB_REF_NAME: $SANITIZED_REF_NAME"
+          IMAGE_NAME="ghcr.io/${GITHUB_REPOSITORY}:${SANITIZED_REF_NAME}"
+          echo "Image name: $IMAGE_NAME"
+          echo "image_name=$IMAGE_NAME" >> $GITHUB_OUTPUT
       - name: Free Disk Space (Ubuntu)
         uses: jlumbroso/free-disk-space@main
         with:
@@ -39,7 +52,7 @@ jobs:
           cache-to: type=gha,mode=max`
           file: util/container/Dockerfile
           push: true
-          tags: ghcr.io/${{ github.repository_owner }}/snitch_cluster:${{ github.ref_name }}
+          tags: ${{ steps.image_name.outputs.image_name }}
 
   ########
   # Docs #
@@ -53,7 +66,7 @@ jobs:
       github.event_name != 'pull_request' ||
       github.event.pull_request.head.repo.full_name != github.repository
     container:
-      image: ghcr.io/${{ github.repository_owner }}/snitch_cluster:${{ github.ref_name }}
+      image: ${{ needs.build-docker.outputs.image_name }}
     steps:
       - uses: actions/checkout@v2
       - name: Build docs
@@ -93,7 +106,7 @@ jobs:
       github.event_name != 'pull_request' ||
       github.event.pull_request.head.repo.full_name != github.repository
     container:
-      image: ghcr.io/${{ github.repository_owner }}/snitch_cluster:${{ github.ref_name }}
+      image: ${{ needs.build-docker.outputs.image_name }}
     steps:
       - uses: actions/checkout@v2
       - name: Run pytest
@@ -111,7 +124,7 @@ jobs:
       github.event_name != 'pull_request' ||
       github.event.pull_request.head.repo.full_name != github.repository
     container:
-      image: ghcr.io/${{ github.repository_owner }}/snitch_cluster:${{ github.ref_name }}
+      image: ${{ needs.build-docker.outputs.image_name }}
     steps:
       - uses: actions/checkout@v2
         with:
@@ -161,7 +174,7 @@ jobs:
       github.event_name != 'pull_request' ||
       github.event.pull_request.head.repo.full_name != github.repository
     container:
-      image: ghcr.io/${{ github.repository_owner }}/snitch_cluster:${{ github.ref_name }}
+      image: ${{ needs.build-docker.outputs.image_name }}
     steps:
       - uses: actions/checkout@v4
         with: