Update dependency mocha to v9

Author: renovate-bot

package.json

@@ -81,7 +81,7 @@
     "eslint-plugin-vue": "^7.9.0",
     "eslint-plugin-yml": "^0.9.0",
     "eslint4b": "^7.25.0",
-    "mocha": "^8.3.2",
+    "mocha": "^9.0.0",
     "nyc": "^15.1.0",
     "pako": "^2.0.3",
     "prettier": "^2.2.1",