fix: upgrade vue-clipboard2 from 0.2.1 to 0.3.1

Snyk has created this PR to upgrade vue-clipboard2 from 0.2.1 to 0.3.1.

See this package in NPM:
https://www.npmjs.com/package/vue-clipboard2

See this project in Snyk:
https://app.snyk.io/org/santosomar/project/cc4d13f0-f845-4efe-9864-aff5734bcb61?utm_source=github&utm_medium=upgrade-pr

Author: snyk-bot

ui/package-lock.json

@@ -11,7 +11,7 @@
     "axios": "^0.18.1",
     "babel-runtime": "^6.26.0",
     "vue": "^2.5.17",
-    "vue-clipboard2": "^0.2.1",
+    "vue-clipboard2": "^0.3.1",
     "vue-markdown": "^2.2.4",
     "vue-meta": "^1.5.8",
     "vue-router": "^3.0.1",