Update dependency typescript to v2.8.1

Author: renovate-bot

package.json

@@ -28,6 +28,6 @@
     "ts-jest": "22.0.2",
     "ts-node": "4.1.0",
     "tslint": "5.9.1",
-    "typescript": "2.7.2"
+    "typescript": "2.8.1"
   }
 }

yarn.lock

@@ -4208,9 +4208,9 @@ type-detect@^4.0.0:
   version "4.0.3"
   resolved "https://registry.yarnpkg.com/type-detect/-/type-detect-4.0.3.tgz#0e3f2670b44099b0b46c284d136a7ef49c74c2ea"
 
-typescript@2.7.2:
-  version "2.7.2"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.7.2.tgz#2d615a1ef4aee4f574425cdff7026edf81919836"
+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"