Allow Starlette 0.38.1

[musicinmybrain]

I need to loosen the dependency bound for the package in the development (Rawhide/F41) and latest stable (F40) versions of Fedora Linux, so I’m offering the change as a PR.

https://github.com/encode/starlette/releases/tag/0.38.0

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Added

• Allow use of memoryview in StreamingResponse and Response
• Send 404 instead of 500 when filename requested is too long on StaticFiles

Changed

• Fail fast on invalid Jinja2Template instantiation parameters
• Check endpoint handler is async only once

Fixed

• Add proper synchronization to WebSocketTestSession

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I tested this with tox -e testcore and did not observe any regressions.

[ivankravets]

Thanks for the PR!