chore: add forgotten line continuation

Author: rjaegers

.github/workflows/build-push.yml

@@ -132,7 +132,7 @@ jobs:
       - name: Create manifest list and push
         working-directory: ${{ runner.temp }}/digests
         run: |
-          docker buildx imagetools create
+          docker buildx imagetools create \
             $(echo '${{ steps.metadata.outputs.json }}' | jq -r '.tags | map("--tag " + .) | join(" ")') \
             $(echo '${{ steps.metadata.outputs.json }}' | jq -r '.annotation | map("--annotation " + .) | join(" ")') \
             $(printf '${{ env.REGISTRY }}/${{ github.repository }}-${{ matrix.flavor }}@sha256:%s ' *)