fix: resolve all cargo clippy warnings

- Fix toml version requirement metadata warning
- Replace clone() with std::slice::from_ref()
- Collapse nested if statements
- Add #[allow(dead_code)] to test utility functions
- Fix unused imports and variables in tests
- Use unwrap_or_else instead of expect with format!

wtismycode-core/tests/caching.rs

@@ -2,7 +2,6 @@
 //!
 //! These tests verify that the caching functionality works correctly.
 
-use std::path::Path;
 use std::fs;
 use tempfile::TempDir;
 use wtismycode_core::{Config, python_analyzer::PythonAnalyzer};