Update dependency @vue/test-utils to v2.0.0-rc.6

Author: renovate-bot

frontend/package-lock.json

@@ -35,7 +35,7 @@
     "@vue/cli-service": "4.5.12",
     "@vue/compiler-sfc": "3.0.11",
     "@vue/eslint-config-typescript": "7.0.0",
-    "@vue/test-utils": "2.0.0-rc.4",
+    "@vue/test-utils": "2.0.0-rc.6",
     "babel-jest": "26.6.3",
     "chromedriver": "89.0.0",
     "eslint": "6.8.0",