Update dependency @types/mocha to v9

Author: renovate-bot

package.json

@@ -49,7 +49,7 @@
         "@types/eslint": "^7.2.0",
         "@types/eslint-scope": "^3.7.0",
         "@types/eslint-visitor-keys": "^1.0.0",
-        "@types/mocha": "^8.0.0",
+        "@types/mocha": "^9.0.0",
         "@types/node": "^14.0.13",
         "@typescript-eslint/eslint-plugin": "^4.9.1",
         "@typescript-eslint/parser": "^4.9.1",