chore(package): update serverless-offline to version 3.28.1

Author: greenkeeper[bot]

package.json

@@ -50,7 +50,7 @@
     "rimraf": "^2.6.2",
     "serverless-aws-documentation": "^1.1.0",
     "serverless-domain-manager": "^2.6.5",
-    "serverless-offline": "^3.27.0",
+    "serverless-offline": "^3.28.1",
     "serverless-plugin-typescript": "^1.1.5",
     "serverless-stack-output": "^0.2.3",
     "source-map-support": "^0.5.9",