chore(deps): update devdependency @vue/test-utils to v2

Author: renovate[bot]

package.json

@@ -69,7 +69,7 @@
     "@babel/preset-env": "^7.10.2",
     "@nuxtjs/eslint-config": "^3.0.0",
     "@vue/server-test-utils": "^1.0.3",
-    "@vue/test-utils": "^1.0.3",
+    "@vue/test-utils": "^2.4.6",
     "@vuepress/plugin-google-analytics": "^1.5.1",
     "@vuepress/plugin-pwa": "^1.5.1",
     "babel-core": "^7.0.0-bridge",