chore(package): update @vue/cli-plugin-typescript to version 4.0.3

Closes #37

Author: greenkeeper[bot]

package.json

@@ -30,7 +30,7 @@
   "devDependencies": {
     "@types/jest": "^24.0.11",
     "@vue/cli-plugin-eslint": "^3.5.0",
-    "@vue/cli-plugin-typescript": "^3.5.0",
+    "@vue/cli-plugin-typescript": "^4.0.3",
     "@vue/cli-plugin-unit-jest": "^3.5.1",
     "@vue/cli-service": "^3.5.0",
     "@vue/eslint-config-prettier": "^4.0.1",