Using ReadToEndAsync to replace ReadToEnd

[catcherwong]

Based on Avoid using synchronous Read/Write overloads on HttpRequest.Body and HttpResponse.Body and many samples of azure function, such as

https://github.com/azure-samples/azure-sql-binding-func-dotnet-todo/blob/main/PostToDo.cs#L27

and

https://github.com/azure-samples/media-services-v3-dotnet-core-functions-integration/blob/main/Functions/CreateEmptyAsset.cs#L86

Using ReadToEndAsync to replace ReadToEnd may be better here.

[pjirsa]

@all-contributors add @catcherwong for code

[allcontributors[bot]]

@pjirsa

This project's configuration file has malformed JSON: .all-contributorsrc. Error:: Unexpected token } in JSON at position 4654

[pjirsa]

@all-contributors add @catcherwong for code

[allcontributors[bot]]

@pjirsa

I've put up a pull request to add @catcherwong! :tada: