chore(deps): update commitlint monorepo to v20

Author: renovate[bot]

package.json

@@ -47,8 +47,8 @@
     "sourcegraph": ">=25.7.0"
   },
   "devDependencies": {
-    "@commitlint/cli": "^19.3.0",
-    "@commitlint/config-conventional": "^19.2.2",
+    "@commitlint/cli": "^20.1.0",
+    "@commitlint/config-conventional": "^20.0.0",
     "@sourcegraph/eslint-config": "^0.37.1",
     "@sourcegraph/prettierrc": "^2.2.0",
     "@sourcegraph/tsconfig": "^4.0.1",