Bump typedoc from 0.20.37 to 0.21.0 in /glean

Bumps [typedoc](https://github.com/TypeStrong/TypeDoc) from 0.20.37 to 0.21.0.
- [Release notes](https://github.com/TypeStrong/TypeDoc/releases)
- [Commits](TypeStrong/typedoc@v0.20.37...v0.21.0)

---
updated-dependencies:
- dependency-name: typedoc
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

glean/package-lock.json

@@ -102,7 +102,7 @@
     "sinon": "^11.0.0",
     "ts-loader": "^9.0.1",
     "ts-node": "^10.0.0",
-    "typedoc": "^0.20.37",
+    "typedoc": "^0.21.0",
     "typescript": "^4.3.4",
     "web-ext-types": "^3.2.1",
     "webpack": "^5.39.1",