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

Closes #240

Author: greenkeeper[bot]

package.json

@@ -104,7 +104,7 @@
     "prettier": "^1.19.1",
     "shelljs": "^0.8.3",
     "supertest": "^4.0.2",
-    "ts-jest": "^24.2.0",
+    "ts-jest": "^26.0.0",
     "ts-node": "^8.5.4",
     "tslint": "^5.20.1",
     "tslint-config-prettier": "^1.18.0",