Update to latest `actions/publish-action`

To avoid Actions core deprecation messages.

https://github.com/actions/publish-action/releases/tag/v0.2.1

.github/workflows/release-new-action-version.yml

@@ -21,7 +21,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Update the ${{ env.TAG_NAME }} tag
-        uses: actions/publish-action@v0.1.0
+        uses: actions/publish-action@v0.2.1
         with:
           source-tag: ${{ env.TAG_NAME }}
           slack-webhook: ${{ secrets.SLACK_WEBHOOK }}