chore(deps): update dependency typescript to v3.9.6

Author: renovate-bot

package-lock.json

@@ -39,7 +39,7 @@
     "ts-jest": "24.1.0",
     "tslint": "5.20.0",
     "tslint-config-prettier": "1.18.0",
-    "typescript": "3.6.3"
+    "typescript": "3.9.6"
   },
   "dependencies": {
     "codecov": "3.6.1",