update token generation

.github/workflows/release-please.yml

@@ -13,9 +13,15 @@ jobs:
   release-please:
     runs-on: ubuntu-latest
     steps:
+      - name: Generate token
+        id: generate-token
+        uses: tibdex/github-app-token@v2
+        with:
+          app_id: ${{ vars.STEWARD_APP_ID }}
+          private_key: ${{ secrets.STEWARD_PRIVATE_KEY }}
       - uses: google-github-actions/release-please-action@v4
         with:
           # Version is determined by sbt-ci-release (which uses sbt-dynver)
           # Actual release code is in `./scala.yml`
           release-type: simple
-          token: ${{ secrets.RELEASE_PLEASE_TOKEN }}
+          token: ${{ steps.generate-token.outputs.token }}