Update dependency prettier to v2 (#57)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

Author: renovate[bot]

package-lock.json

@@ -43,7 +43,7 @@
     "eslint-plugin-promise": "4.2.1",
     "eslint-plugin-standard": "4.0.1",
     "jest": "24.9.0",
-    "prettier": "1.19.1",
+    "prettier": "2.0.5",
     "ts-jest": "24.2.0",
     "typescript": "3.7.4",
     "vue": "2.6.11",