GraphQL integration does not work w/ graphl-core versions > 2

[mecampbellsoup]

Checklist

• The bug is reproducible against the latest release and/or master.
• There are no similar issues or pull requests to fix it yet.

Describe the bug

When following the Starlette GraphQL docs regarding GraphQL integration, if you install graphql-core versions > 2 (i.e. non-legacy core library), you will see that the module graphql.execution.executors.asyncio.AsyncioExecutor no longer exists.

I asked about this in the GraphQL core project and they indicated that as of graphql-core >=3 the executors had been discarded as they were now async by default, roughly speaking (I'm paraphrasing, please see the issue I linked to for context).

I didn't see any open issues regarding support for the new graphql-core versions - is this in the works, by any chance? The legacy project is now unsupported.

Environment

• OS: Linux (by way of minikube)
• Python version: 3.9.0
• Starlette version: 0.13.16

Additional context

graphql-python/graphql-core#121
https://github.com/graphql-python/graphql-core-legacy

[Kludex]

Starlette deprecated built-in GraphQL support.

Check #1135 for more details.