deps: bump @actions/github from 3.0.0 to 4.0.0 (#172)

Bumps [@actions/github](https://github.com/actions/toolkit/tree/HEAD/packages/github) from 3.0.0 to 4.0.0.
- [Release notes](https://github.com/actions/toolkit/releases)
- [Changelog](https://github.com/actions/toolkit/blob/master/packages/github/RELEASES.md)
- [Commits](https://github.com/actions/toolkit/commits/HEAD/packages/github)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -53,7 +53,7 @@
   "homepage": "https://github.com/peaceiris/actions-label-commenter#readme",
   "dependencies": {
     "@actions/core": "^1.2.4",
-    "@actions/github": "^3.0.0",
+    "@actions/github": "^4.0.0",
     "js-yaml": "^3.14.0",
     "mustache": "^4.0.1"
   },