Update typescript to 3.9

Author: bidoubiwa

package.json

@@ -86,6 +86,6 @@
     "rollup-plugin-typescript2": "^0.27.0",
     "shx": "^0.3.2",
     "ts-jest": "^25.3.0",
-    "typescript": "^3.8.3"
+    "typescript": "3.9.3"
   }
 }