fix(mocha): disable SSR optimization for Vue 3 testing (#6097)

Fixes vuejs/vue-loader#1734

Author: haoqunjiang

Diff for: package.json

@@ -72,7 +72,7 @@
     "thread-loader": "^3.0.0",
     "url-loader": "^4.1.1",
     "vue-loader": "^15.9.2",
-    "vue-loader-v16": "npm:vue-loader@^16.0.0-beta.7",
+    "vue-loader-v16": "npm:vue-loader@^16.1.0",
     "vue-style-loader": "^4.1.2",
     "webpack": "^4.0.0",
     "webpack-bundle-analyzer": "^3.8.0",