Update dependency typescript to v3.9.3 (#588)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

Author: renovate[bot]

package-lock.json

@@ -16,7 +16,7 @@
         "glob": "7.1.6",
         "strip-json-comments": "3.1.0",
         "tslint": "6.1.2",
-        "typescript": "3.9.2"
+        "typescript": "3.9.3"
     },
     "devDependencies": {
         "@babel/core": "7.9.6",