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/theme_importer/Cargo.toml

@@ -15,7 +15,6 @@ gpui.workspace = true
 indexmap.workspace = true
 log.workspace = true
 palette.workspace = true
-rust-embed.workspace = true
 serde.workspace = true
 serde_json.workspace = true
 serde_json_lenient.workspace = true

crates/theme_importer/src/assets.rs

@@ -1,27 +0,0 @@
-use std::borrow::Cow;
-
-use anyhow::{Context as _, Result};
-use gpui::{AssetSource, SharedString};
-use rust_embed::RustEmbed;
-
-#[derive(RustEmbed)]
-#[folder = "../../assets"]
-#[include = "fonts/**/*"]
-#[exclude = "*.DS_Store"]
-pub struct Assets;
-
-impl AssetSource for Assets {
-    fn load(&self, path: &str) -> Result<Option<Cow<'static, [u8]>>> {
-        Self::get(path)
-            .map(|f| f.data)
-            .with_context(|| format!("could not find asset at path {path:?}"))
-            .map(Some)
-    }
-
-    fn list(&self, path: &str) -> Result<Vec<SharedString>> {
-        Ok(Self::iter()
-            .filter(|p| p.starts_with(path))
-            .map(SharedString::from)
-            .collect())
-    }
-}

crates/theme_importer/src/main.rs

@@ -1,4 +1,3 @@
-mod assets;
 mod color;
 mod vscode;