Update dependency typescript to v4 (#686)

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

Author: renovate[bot]

package-lock.json

@@ -16,7 +16,7 @@
         "glob": "7.1.6",
         "strip-json-comments": "3.1.1",
         "tslint": "6.1.3",
-        "typescript": "3.9.7"
+        "typescript": "4.0.2"
     },
     "devDependencies": {
         "@babel/core": "7.11.1",