Update Microsoft.IO.RecyclableStreams to v3

[ntwilson]

Types of changes

What types of changes does your code introduce to FSharp.Control.WebSockets?
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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

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• Build and tests pass locally
• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have added necessary documentation (if appropriate)

Further comments

Fixes #9. There were no code changes, it just needed to be recompiled with the new package version. The failure was due to them changing the return type of a method from MemoryStream to RecyclableMemoryStream, so the method wasn't found at runtime, but that didn't need anything to change in the code.

Paket added a bunch of other unrelated changes. At work, we typically just ignore those other changes. Would you prefer they were reverted?

[TheAngryByrd]

Thanks for this! Changes look fine. I’ll merge and release when I’m near my computer next.