chore: enable clippy::redundant_clone (#3489)

Created this PR by:

- adding `redundant_clone` to `[workspace.lints.clippy]` in
`cargo-rs/Cargol.toml`
- running `cargo clippy --tests --fix`
- running `just fmt`

Though I had to clean up one instance of the following that resulted:

```rust
let codex = codex;
```

codex-rs/tui/src/bottom_pane/textarea.rs

@@ -649,9 +649,7 @@ impl TextArea {
     }
 
     fn add_element(&mut self, range: Range<usize>) {
-        let elem = TextElement {
-            range: range.clone(),
-        };
+        let elem = TextElement { range };
         self.elements.push(elem);
         self.elements.sort_by_key(|e| e.range.start);
     }