Http Respond as application/expo+json and application/json

[Ddv0623]

Hi, I am currently working on create a .NET Core server to serve the expo updates. In the example here I see that it always responded with content-type: multipart/mixed. while in the specification it is allowed to responded as application/expo+json and application/json. Could you guys update the example here to show us how to implement it correctly? Also I see that npm expo-updates is release version 0.23.0 with tag next? Will there be any breaking change in the server side to support newer version of expo-updates