Update dependency @vue/test-utils to v1.3.6

Author: renovate[bot]

package.json

@@ -17,7 +17,7 @@
   "devDependencies": {
     "@vue/cli-plugin-babel": "4.4.4",
     "@vue/cli-plugin-unit-mocha": "4.4.4",
-    "@vue/test-utils": "1.0.0-beta.25",
+    "@vue/test-utils": "1.3.6",
     "axios": "0.18.1",
     "chai": "4.2.0",
     "coffee-loader": "0.9.0",