Bump @octokit/rest from 15.13.0 to 16.9.0

Bumps [@octokit/rest](https://github.com/octokit/rest.js) from 15.13.0 to 16.9.0.
- [Release notes](https://github.com/octokit/rest.js/releases)
- [Commits](https://github.com/octokit/rest.js/compare/v15.13.0...v16.9.0)
Signed-off-by: dependabot[bot] <support@dependabot.com>

package.json

@@ -7,7 +7,7 @@
   "bugs": "https://github.com/hypothesis/client/issues",
   "repository": "hypothesis/client",
   "devDependencies": {
-    "@octokit/rest": "^15.13.0",
+    "@octokit/rest": "^16.9.0",
     "angular": "^1.7.5",
     "angular-mocks": "^1.7.5",
     "angular-route": "^1.7.5",