chore(deps): update commitlint monorepo to v21

Author: renovate[bot]

package.json

@@ -21,8 +21,8 @@
     ]
   },
   "devDependencies": {
-    "@commitlint/cli": "^17.8.1",
-    "@commitlint/config-conventional": "^17.8.1",
+    "@commitlint/cli": "^21.0.0",
+    "@commitlint/config-conventional": "^21.0.0",
     "@sourcegraph/eslint-config": "^0.33.0",
     "@sourcegraph/prettierrc": "^3.0.3",
     "@sourcegraph/tsconfig": "^4.0.1",