chore(package): update @types/jest to version 23.3.1

Closes #32

Author: greenkeeper[bot]

package.json

@@ -36,7 +36,7 @@
     "@koa/cors": "^2.2.1",
     "@types/aws-lambda": "^0.0.35",
     "@types/http-errors": "^1.6.1",
-    "@types/jest": "^22.2.2",
+    "@types/jest": "^23.3.1",
     "@types/node": "^10.0.3",
     "@types/sinon": "^4.3.0",
     "jest": "^22.4.3",