chore(deps): update dev dependency typescript to v4 (#718)

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

Author: renovate[bot]

package-lock.json

@@ -41,7 +41,7 @@
     "puppeteer": "3.3.0",
     "rimraf": "3.0.2",
     "serve": "11.3.2",
-    "typescript": "3.9.7"
+    "typescript": "4.0.2"
   },
   "keywords": [
     "if-needed",