message: ci: fix bad reference to `head` property in rebase-pr script
  Update rebase-pr script to properly reference a property on
  the refs object using `target` rather than the previously
  named `head`.
  PR Close
diff: @@ -86,7 +86,7 @@ async function _main() {
  Rebase instructions for PR Author, please run the following commands:
  git fetch upstream ${refs.base.ref};
  - git checkout ${refs.head.ref};
  + git checkout ${refs.target.ref};
  git rebase upstream/${refs.base.ref};
  git push --force-with-lease;
  `);
  