Update dependency typescript to v2.8.3

Author: renovate-bot

package.json

@@ -38,7 +38,7 @@
     "standard": "10.0.3",
     "ts-jest": "22.0.4",
     "tslint": "5.9.1",
-    "typescript": "2.7.2"
+    "typescript": "2.8.3"
   },
   "keywords": [
     "bot",

yarn.lock

@@ -3742,9 +3742,9 @@ typedarray@^0.0.6:
   version "0.0.6"
   resolved "https://registry.yarnpkg.com/typedarray/-/typedarray-0.0.6.tgz#867ac74e3864187b1d3d47d996a78ec5c8830777"
 
-typescript@2.7.2:
-  version "2.7.2"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.7.2.tgz#2d615a1ef4aee4f574425cdff7026edf81919836"
+typescript@2.8.3:
+  version "2.8.3"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.8.3.tgz#5d817f9b6f31bb871835f4edf0089f21abe6c170"
 
 uglify-js@^2.6:
   version "2.8.29"