Bump Rust to 1.90 (#38436)

Release Notes:

- N/A

---------

Co-authored-by: Nia Espera <nia@zed.dev>
Co-authored-by: Julia Ryan <juliaryan3.14@gmail.com>

crates/git_ui/src/git_panel_settings.rs

@@ -9,14 +9,6 @@ use ui::{
 };
 use workspace::dock::DockPosition;
 
-#[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
-pub struct ScrollbarSettingsContent {
-    /// When to show the scrollbar in the git panel.
-    ///
-    /// Default: inherits editor scrollbar settings
-    pub show: Option<Option<ShowScrollbar>>,
-}
-
 #[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
 pub struct ScrollbarSettings {
     pub show: Option<ShowScrollbar>,