chore(deps): bump @slack/bolt in /examples/custom-properties

Bumps [@slack/bolt](https://github.com/slackapi/bolt-js) from 3.22.0 to 4.2.0.
- [Release notes](https://github.com/slackapi/bolt-js/releases)
- [Commits](https://github.com/slackapi/bolt-js/compare/@slack/[email protected]...@slack/[email protected])

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

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

examples/custom-properties/package.json

@@ -10,6 +10,6 @@
   },
   "license": "MIT",
   "dependencies": {
-    "@slack/bolt": "^3"
+    "@slack/bolt": "^4"
   }
 }