chore(package): update ts-jest to version 25.2.0

Closes #63

Author: greenkeeper[bot]

package.json

@@ -72,7 +72,7 @@
     "rollup-plugin-terser": "^5.1.2",
     "sass-loader": "^8.0.0",
     "style-loader": "^1.0.0",
-    "ts-jest": "^24.0.0",
+    "ts-jest": "^25.2.0",
     "tslint": "^5.12.1",
     "tslint-config-airbnb": "^5.11.1",
     "tslint-loader": "^3.5.4",