action: publish docker manifest only for latest

The PR #584 overlooked a scenario involving more than two elements
in `steps.meta.outputs.tags`. This commit addresses that by iterating
over the tags and creating/pushing a manifest only for tags ending
with `latest`.

Fixes: #583

Signed-off-by: Hyounggyu Choi <Hyounggyu.Choi@ibm.com>

.github/workflows/release.yml

@@ -171,7 +171,11 @@ jobs:
           images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
       - name: Publish manifest for multi-arch image
         run: |
-          docker manifest create ${{ steps.meta.outputs.tags }} \
-          --amend ${{ steps.meta.outputs.tags }}-amd64 --amend ${{ steps.meta.outputs.tags }}-arm64 \
-          --amend ${{ steps.meta.outputs.tags }}-s390x --amend ${{ steps.meta.outputs.tags }}-ppc64le
-          docker manifest push ${{ steps.meta.outputs.tags }}
+          for tag in $(echo "${{ steps.meta.outputs.tags }}" | tr ' ' '\n'); do
+            if [[ "${tag}" == *latest ]]; then
+              docker manifest create "${tag}" \
+              --amend "${tag}-amd64" --amend "${tag}-arm64" \
+              --amend "${tag}-s390x" --amend "${tag}-ppc64le"
+              docker manifest push "${tag}"
+            fi
+          done