chore(package): update ts-jest to version 23.1.2

Closes #3

Author: greenkeeper[bot]

package.json

@@ -32,7 +32,7 @@
     "jest": "^23.2.0",
     "prettier": "^1.13.6",
     "source-map": "^0.7.3",
-    "ts-jest": "^22.4.6",
+    "ts-jest": "^23.1.2",
     "tsc-watch": "^1.0.22",
     "tslint": "^5.10.0",
     "tslint-eslint-rules": "^5.3.1",