chore: Bump Rust version to 1.88 (#33439)

Goodies in this version:
- if-let chains 🎉
- Better compiler perf for Zed
(https://github.com/rust-lang/rust/pull/138522)

For more, see: https://releases.rs/docs/1.88.0/

Release Notes:

- N/A

---------

Co-authored-by: Junkui Zhang <364772080@qq.com>

crates/project/src/project_tests.rs

@@ -7502,13 +7502,13 @@ async fn test_staging_random_hunks(
         if hunk.status().has_secondary_hunk() {
             log::info!("staging hunk at {row}");
             uncommitted_diff.update(cx, |diff, cx| {
-                diff.stage_or_unstage_hunks(true, &[hunk.clone()], &snapshot, true, cx);
+                diff.stage_or_unstage_hunks(true, std::slice::from_ref(hunk), &snapshot, true, cx);
             });
             hunk.secondary_status = SecondaryHunkRemovalPending;
         } else {
             log::info!("unstaging hunk at {row}");
             uncommitted_diff.update(cx, |diff, cx| {
-                diff.stage_or_unstage_hunks(false, &[hunk.clone()], &snapshot, true, cx);
+                diff.stage_or_unstage_hunks(false, std::slice::from_ref(hunk), &snapshot, true, cx);
             });
             hunk.secondary_status = SecondaryHunkAdditionPending;
         }