remove redundant code

[thiagodebastos]

This cleans up some unused code, removing a warning that comes up during build of helix source:

helix-term/src/ui/picker.rs

• retain_mut::RetainMut is no longer needed since vec::vec::retain_mut has been stabilised:
  • Stabilize feature vec_retain_mut on Vec and VecDeque rust-lang/rust#95491.
  • https://doc.rust-lang.org/alloc/vec/struct.Vec.html#method.retain_mut

[thiagodebastos]

Sorry, I am still learning rust. I take it this didn't fail locally because I'm using Rust nightly, and the merged RetainMut is only available on nightly?

[archseer]

Exactly. It'll be stable in two rust releases (target is 1.61.0 rust-lang/rust@c90a947)

[thiagodebastos]

@archseer Fantastic, thanks for clearing that up. Should I then close this PR?

[pickfire]

https://www.whatrustisit.com/

[archseer]

Yeah, we'll patch it when it's available

[thiagodebastos]

Thank you for the feedback guys and thank you for the link @pickfire !