chore: Bump Rust edition to 2024 (#27800)

Follow-up to https://github.com/zed-industries/zed/pull/27791

Release Notes:

- N/A

crates/markdown_preview/src/markdown_elements.rs

@@ -1,5 +1,5 @@
 use gpui::{
-    px, FontStyle, FontWeight, HighlightStyle, SharedString, StrikethroughStyle, UnderlineStyle,
+    FontStyle, FontWeight, HighlightStyle, SharedString, StrikethroughStyle, UnderlineStyle, px,
 };
 use language::HighlightId;
 use std::{fmt::Display, ops::Range, path::PathBuf};