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/gpui/src/util.rs

@@ -83,34 +83,6 @@ where
     timer.race(future).await
 }
 
-#[cfg(any(test, feature = "test-support"))]
-pub struct CwdBacktrace<'a>(pub &'a backtrace::Backtrace);
-
-#[cfg(any(test, feature = "test-support"))]
-impl std::fmt::Debug for CwdBacktrace<'_> {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        use backtrace::{BacktraceFmt, BytesOrWideString};
-
-        let cwd = std::env::current_dir().unwrap();
-        let cwd = cwd.parent().unwrap();
-        let mut print_path = |fmt: &mut std::fmt::Formatter<'_>, path: BytesOrWideString<'_>| {
-            std::fmt::Display::fmt(&path, fmt)
-        };
-        let mut fmt = BacktraceFmt::new(f, backtrace::PrintFmt::Full, &mut print_path);
-        for frame in self.0.frames() {
-            let mut formatted_frame = fmt.frame();
-            if frame
-                .symbols()
-                .iter()
-                .any(|s| s.filename().map_or(false, |f| f.starts_with(cwd)))
-            {
-                formatted_frame.backtrace_frame(frame)?;
-            }
-        }
-        fmt.finish()
-    }
-}
-
 /// Increment the given atomic counter if it is not zero.
 /// Return the new value of the counter.
 pub(crate) fn atomic_incr_if_not_zero(counter: &AtomicUsize) -> usize {