chore(deps): update @slack/bolt requirement in /examples/deploy-heroku

Updates the requirements on [@slack/bolt](https://github.com/slackapi/bolt-js) to permit the latest version.
- [Release notes](https://github.com/slackapi/bolt-js/releases)
- [Commits](https://github.com/slackapi/bolt-js/compare/@slack/bolt@4.6.0...@slack/bolt@4.7.0)

---
updated-dependencies:
- dependency-name: "@slack/bolt"
  dependency-version: 4.7.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

examples/deploy-heroku/package.json

@@ -9,6 +9,6 @@
   },
   "license": "MIT",
   "dependencies": {
-    "@slack/bolt": "^4.6.0"
+    "@slack/bolt": "^4.7.0"
   }
 }