chore(package): update ts-jest to version 26.0.0

Closes #42

Author: greenkeeper[bot]

package.json

@@ -31,7 +31,7 @@
     "nodemon": "^1.18.5",
     "nsp": "^3.1.0",
     "supertest": "^3.3.0",
-    "ts-jest": "^23.10.4",
+    "ts-jest": "^26.0.0",
     "ts-node": "^7.0.1",
     "tslint": "^5.11.0",
     "typescript": "^3.1.6"