Update to latest `actions/publish-action` (#363)

To avoid Actions core deprecation messages.

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

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

@@ -22,7 +22,7 @@ jobs:
     steps:
     - name: Update the ${{ env.TAG_NAME }} tag
       id: update-major-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 }}