fix(package): update typescript to version 2.6.1

Closes #359

Author: greenkeeper[bot]

package.json

@@ -49,7 +49,7 @@
     "rxjs": "^5.5.0",
     "semaphore-async-await": "^1.5.1",
     "string-similarity": "^1.1.0",
-    "typescript": "2.4.2",
+    "typescript": "2.6.1",
     "vscode-jsonrpc": "^3.3.1",
     "vscode-languageserver": "^3.1.0",
     "vscode-languageserver-types": "^3.0.3"