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/exec/tests/suite/common.rs

@@ -61,7 +61,7 @@ pub(crate) async fn run_e2e_exec_test(cwd: &Path, response_streams: Vec<String>)
         .context("should find binary for codex-exec")
         .expect("should find binary for codex-exec")
         .current_dir(cwd.clone())
-        .env("CODEX_HOME", cwd.clone())
+        .env("CODEX_HOME", cwd)
         .env("OPENAI_API_KEY", "dummy")
         .env("OPENAI_BASE_URL", format!("{uri}/v1"))
         .arg("--skip-git-repo-check")