Update dependency typescript to v2.8.1

Author: renovate-bot

package.json

@@ -20,7 +20,7 @@
     "ts-jest": "21.1.3",
     "tslint": "5.8.0",
     "tslint-config-airbnb": "5.3.0",
-    "typescript": "2.5.3"
+    "typescript": "2.8.1"
   },
   "dependencies": {},
   "jest": {

yarn.lock

@@ -3017,9 +3017,9 @@ type-check@~0.3.2:
   dependencies:
     prelude-ls "~1.1.2"
 
-typescript@2.5.3:
-  version "2.5.3"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.5.3.tgz#df3dcdc38f3beb800d4bc322646b04a3f6ca7f0d"
+typescript@2.8.1:
+  version "2.8.1"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.8.1.tgz#6160e4f8f195d5ba81d4876f9c0cc1fbc0820624"
 
 uglify-js@^2.6:
   version "2.8.29"