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

Closes #43

Author: greenkeeper[bot]

package.json

@@ -40,7 +40,7 @@
     "eslint": "^6.0.0",
     "eslint-plugin-vue": "^5.0.0",
     "jest": "^24.5.0",
-    "ts-jest": "^24.0.0",
+    "ts-jest": "^26.0.0",
     "typescript": "^3.3.4000",
     "vue-template-compiler": "^2.5.21"
   },