Bump MSRV to 1.67.1 and fix CI didn't check MSRV

[rhysd]

Hi,

I investigated why #136 was not caught by CI. And I found that CI workflows for Rust 1.61 was actually using the latest stable toolchain.

This PR fixes the issue. I could confirm 1.61 was used properly on my fork.

info: syncing channel updates for '1.61-x86_64-unknown-linux-gnu'
info: latest update on 2022-05-19, rust version 1.61.0 (fe5b13d68 2022-05-18)

https://github.com/rhysd/arboard/actions/runs/8135373857/job/22229818914

Please note that CI will break after merging this PR. This is because wayland-backend crate requires Rust 1.65 or later.

error: package `wayland-backend v0.3.2` cannot be built because it requires rustc 1.65 or newer, while the currently active rustc version is 1.61.0

I didn't bump the MSRV of this crate in this PR because I'm not understanding the process. (If you prefer bumping MSRV in this PR, please let me know. I'll include the changes.)

[complexspaces]

Thanks for the PR @rhysd. I think we should go ahead and bump the MSRV in this PR.

because I'm not understanding the process.

All that needs done is:

• Updating the README badge
• Changing the rust-version manifest field
• Bumping the MSRV in CI

1.65 is a reasonable target of "usefulness" because its when GATs became stable. Its also 1.5 years old so there has been ample time for adoption. If anyone comes by at a later point and says this has impacted their project somehow, I'm inclined to just remove wayland testing from our MSRV CI configuration and document the increased requirement. That's more effort then bumping it though so lets try the simpler option first.

[rhysd]

Sure. Thank you for your response with the advices. I'll try to update this branch when I have time, hopefully within a few days.

[rhysd]

After resolving the Rust 1.65 MSRV error, it turned out that more recent version was required by other crate. image crate requires 1.67.1 or newer.

To meet the requirement, I bumped this crate's MSRV to 1.67.1.

[complexspaces]

Thank you again for catching this and putting up a fix.