message: build/release: use "next" if unstable branch
  Re:
diff: @@ -85,7 +85,7 @@ push_and_publish() {
  # push branch and tags to git origin
  git push --no-verify && git push --no-verify origin $NEW_TAG &&
  - if [[ $NEW_VERSION == "prerelease" ]]; then
  + if [[ $RELEASE_BRANCH == "unstable" ]]; then
  # publish to npm with "next" tag
  git tag --force next &&
  git push --no-verify -f origin next &&
  