fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-DOTPROP-543489

package.json

@@ -78,7 +78,7 @@
     "rollup-plugin-uglify": "^2.0.1",
     "stringify-author": "^0.1.3",
     "switchy": "^0.1.0",
-    "update-notifier": "^2.2.0"
+    "update-notifier": "^4.0.0"
   },
   "jest": {
     "coverageDirectory": "./coverage/"