chore: quote var

Author: clemak27

.github/workflows/publish.yaml

@@ -108,7 +108,7 @@ jobs:
         if: github.event_name != 'pull_request' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch)
         run: |
           IMAGE_FULL="${{ env.IMAGE_REGISTRY }}/${{ env.IMAGE_NAME }}"
-          cosign sign -y --key env://COSIGN_PRIVATE_KEY $IMAGE_FULL@$DIGEST
+          cosign sign -y --key env://COSIGN_PRIVATE_KEY "$IMAGE_FULL@$DIGEST"
         env:
           DIGEST: ${{ steps.push.outputs.digest }}
           COSIGN_EXPERIMENTAL: false