build(deps-dev): bump github-label-sync from 2.3.1 to 3.0.0

Bumps [github-label-sync](https://github.com/Financial-Times/github-label-sync) from 2.3.1 to 3.0.0.
- [Release notes](https://github.com/Financial-Times/github-label-sync/releases)
- [Changelog](https://github.com/Financial-Times/github-label-sync/blob/master/CHANGELOG.md)
- [Commits](Financial-Times/github-label-sync@v2.3.1...v3.0.0)

---
updated-dependencies:
- dependency-name: github-label-sync
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

Diff for: package-lock.json

@@ -2,7 +2,7 @@
   "devDependencies": {
     "ajv-cli": "5.0.0",
     "ajv-formats": "3.0.1",
-    "github-label-sync": "2.3.1",
+    "github-label-sync": "3.0.0",
     "markdown-link-check": "3.12.2",
     "markdown-toc": "1.2.0",
     "markdownlint-cli": "0.37.0",