fix(ci): use PAT for release-please to trigger CI on its PRs (#1021)

GitHub prevents events created by GITHUB_TOKEN from triggering other
workflows, so CI checks never run on release-please PRs.
Switch to RP_TOKEN (fine-grained PAT) to fix this.

Author: rmartins90

.github/workflows/release-please.yml

@@ -19,7 +19,7 @@ jobs:
             - uses: googleapis/release-please-action@v4
               id: release
               with:
-                  token: ${{ secrets.GITHUB_TOKEN }}
+                  token: ${{ secrets.RP_TOKEN }}
                   target-branch: main
                   config-file: .github/release-please-config.json
                   manifest-file: .github/release-please-manifest.json