Added tests for reserved scalar names handling (#550)

Co-authored-by: Andrii Chebukin <XperiAndri@Outlook.com>

Release `3.1.0`

Set source for pushing to NuGet

Fixes `System.InvalidOperationException: This JsonSerializerOptions i…

…nstance is read-only or has already been used in serialization or deserialization` (#480)

* Updated NuGet packages

* Attempt to fix publish

* Removed static JSON serializer options instance

Installed `Altair` and `GraphiQL` to sample projects

.AspNetCore: adjusting README to current code usage (#478)

* .AspNetCore: adjusting README to current code usage

  Co-authored by @xperiandri

Updated WebSocket reading logic to eliminate large arrays allocation (#…

…464)

Fixed templates publishing