Bump net2 and miow to get rid of invalid memory layout assumption

[faern]

Fixes #1390

After getting net2 0.2.36 and miow 0.2.2 fixed and published we can bump mio so it forces the usage of dependencies not making invalid memory layout assumptions on std::net::SocketAddr.

[faern]

So, does mio 0.6 support Rust back to 1.18 and this is not negotiable? Then we have a problem. Because net2 won't build on so old Rust. And it's nothing I did with the 0.2.36 changes. net2 has not built worked with so old Rust for many versions from what I can find.

[faern]

Since these other crates in the dependency chain does not regard an MSRV bump as a breaking change, it's somewhat hard for mio to provide that guarantee. I'd argue that the best would be to merge this, bump the MSRV to 1.31.0 (the oldest version I can make it work with) and simply let the (almost guaranteed) very few people using something older simply not bump their mio dependency. They currently can't bump their net2 or miow dependency anyway 🤷.

Every yearly Rust survey have showed that very very few use anything older than the latest stable Rust version.

[Thomasdezeeuw]

@carllerche I don't use Mio v0.6 any more, do you know of any use cases that needs to support < Rust 1.31?

[carllerche]

It should be fine. We just need to support 6 month old Rust.

[Thomasdezeeuw]

Thanks for all the work @faern.

[faern]

@Thomasdezeeuw Will you release 0.6.23 now or does that release wait for something more?

[Thomasdezeeuw]

Waiting on #1353.