refactor(lints): add lints to scrollbar (#974)

examples/scrollbar.rs

@@ -13,6 +13,9 @@
 //! [examples]: https://github.com/ratatui-org/ratatui/blob/main/examples
 //! [examples readme]: https://github.com/ratatui-org/ratatui/blob/main/examples/README.md
 
+#![warn(clippy::pedantic)]
+#![allow(clippy::wildcard_imports)]
+
 use std::{
     error::Error,
     io,
@@ -107,6 +110,7 @@ fn run_app<B: Backend>(
     }
 }
 
+#[allow(clippy::too_many_lines, clippy::cast_possible_truncation)]
 fn ui(f: &mut Frame, app: &mut App) {
     let size = f.size();
 

src/widgets/scrollbar.rs

@@ -1,3 +1,12 @@
+#![warn(clippy::pedantic)]
+#![allow(
+    clippy::cast_possible_truncation,
+    clippy::cast_precision_loss,
+    clippy::cast_sign_loss,
+    clippy::module_name_repetitions,
+    clippy::wildcard_imports
+)]
+
 use std::iter;
 
 use strum::{Display, EnumString};
@@ -523,7 +532,7 @@ impl Scrollbar<'_> {
     ///
     /// This method returns the length of the start, thumb, and end as a tuple.
     fn part_lengths(&self, area: Rect, state: &ScrollbarState) -> (usize, usize, usize) {
-        let track_length = self.track_length_excluding_arrow_heads(area) as f64;
+        let track_length = f64::from(self.track_length_excluding_arrow_heads(area));
         let viewport_length = self.viewport_length(state, area) as f64;
 
         // Ensure that the position of the thumb is within the bounds of the content taking into