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

Closes #12

Author: greenkeeper[bot]

package.json

@@ -35,7 +35,7 @@
     "jest": "^23.6.0",
     "lerna": "^3.4.0",
     "pino": "^5.6.2",
-    "ts-jest": "^24.0.0",
+    "ts-jest": "^25.2.1",
     "typescript": "^3.1.1"
   }
 }