Update dependency mocha to v9

Author: renovate-bot

package-lock.json

@@ -71,7 +71,7 @@
         "eslint-plugin-vue": "^7.5.0",
         "eslint-plugin-yml": "^0.9.0",
         "eslint4b": "^7.3.1",
-        "mocha": "^8.0.0",
+        "mocha": "^9.0.0",
         "nyc": "^15.1.0",
         "prettier": "^2.0.5",
         "raw-loader": "^4.0.1",