Update dependency typescript to v4

Author: renovate-bot

package.json

@@ -23,7 +23,7 @@
     "@types/node": "^14.0.1"
   },
   "devDependencies": {
-    "typescript": "^3.9.2",
+    "typescript": "^4.0.0",
     "jest": "^26.0.1",
     "ts-jest": "^26.0.0",
     "static-type-assert": "^4.0.0",