Removed IAsyncDisposable from CachingTransport

[jamescrosswell]

Resolves #3178

#skip-changelog

[bitsandfoxes]

I'm not sure I get what's going on there. Is this due to us dropping ns2.0? Is removing the interface the right move here, especially since it seems to work on different TFWs? Can we #if around this if this is a target framework issue?

[jamescrosswell]

I'm not sure I get what's going on there. Is this due to us dropping ns2.0? Is removing the interface the right move here, especially since it seems to work on different TFWs? Can we #if around this if this is a target framework issue?

I'm not sure what's going on either... technically that interface should be included in net5.0 and later. The tests fail on net6.0 and net7.0. I think it's something to do with the version of Microsoft.Bcl.AsyncInterfaces that is expected.

However, we don't use or need that interface. If we drop it, it has no impact. If we keep it, our tests fail on a Windows clean build. I figured in the interests of simplicity then, we just drop it. It gives us no benefits and conversely it creates problems we don't need to solve.