chore(deps): update dependency typescript to v4 (#303)

Co-authored-by: Renovate Bot <[email protected]>

Author: renovate[bot]

package.json

@@ -65,7 +65,7 @@
     "serve": "^11.3.2",
     "standardx": "^5.0.0",
     "start-server-and-test": "^1.11.2",
-    "typescript": "^3.7.0"
+    "typescript": "^4.0.0"
   },
   "files": [
     "browser.js",