Fix copy_from_wayland breaking on Nightly

[En-En-Code]

Due to Nightly changes with how UnixStream will handle SIGPIPE, attempting to write to a non-socket UnixStream will fail, a change which appears to be being stabilized.

This resolves the integrations which crash on Nightly by switching to a PipeWriter, a fairly new addition to the standard library, which does not have the non-socket restriction.

I think this bumps MSRV for testwl from 1.83.0 to 1.87.0, but testwl doesn't pass cargo check, not sure why, not sure how integrations still work, but whatever.

[En-En-Code]

Oh, it seems ubuntu-build has not been run since the Rust 1.87.0 release. Should probably add a condition in check_should_build_container to keep Rust up-to-date.

[Supreeeme]

I didn't realize you could create a pipe with std now. You can switch it to use the std method.
You can also set the rust-version field in the testwl Cargo.toml. I can work on updating the ci file.

[En-En-Code]

Oh, setting rust-version is cool but would not resolve the CI.
Yep, std has one-way pipes now. I have a refactor branch, but it is already quite a lot. I can take a job of migrating to std's pipe utilities when I finish with it though.

Edit: rust-version probably is helpful for detcting if the CI should do an update now that I think about it. I set the main project's MSRV as well, so when the refactor to std's pipe happens, it would be an easy confirmation for the CI change.

[En-En-Code]

Okay, I have some CI changes to propose, but since GitHub Actions was a problem I used repeated force-pushing to solve, I made a separate branch and PR for it.