chore(deps): bump @octokit/rest from 20.1.1 to 21.0.0

Bumps [@octokit/rest](https://github.com/octokit/rest.js) from 20.1.1 to 21.0.0.
- [Release notes](https://github.com/octokit/rest.js/releases)
- [Commits](octokit/rest.js@v20.1.1...v21.0.0)

---
updated-dependencies:
- dependency-name: "@octokit/rest"
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -30,7 +30,7 @@
   "homepage": "https://github.com/skjnldsv/backportbot#readme",
   "dependencies": {
     "@octokit/app": "^14.1.0",
-    "@octokit/rest": "^20.1.1",
+    "@octokit/rest": "^21.0.0",
     "@octokit/webhooks": "^13.2.8",
     "p-queue": "^8.0.1",
     "simple-git": "^3.25.0",