chore(package): update ts-jest to version 25.2.1

Closes #282

Author: greenkeeper[bot]

package.json

@@ -110,7 +110,7 @@
     "semantic-release": "^15.9.16",
     "shelljs": "^0.8.3",
     "travis-deploy-once": "^5.0.9",
-    "ts-jest": "^23.10.2",
+    "ts-jest": "^25.2.1",
     "ts-node": "^7.0.1",
     "tslint": "^5.11.0",
     "tslint-config-prettier": "^1.15.0",