This commit addresses all the clippy warnings and errors reported during the linting process. The following issues have been fixed:

- Removed redundant `use` statements for single-component path imports.
- Corrected overindented and lazy doc list items in `spdx_parser`.
- Replaced `clone` on `Copy` types with direct access.
- Simplified unnecessary closure usage with `unwrap_or` and `or`.
- Removed needless borrows by passing values directly.
- Eliminated useless conversions to the same type.

These changes improve code cleanliness and adherence to Rust conventions.