feat: add io/readers to ruff config (#94)

Updated include list to have the io/readers functions and updated the
files so all ruff tests pass.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **New Features**
- Enhanced flexibility in loading feature files by accepting both `Path`
objects and strings.
- Improved error handling and logging for file loading and directory
access.

- **Bug Fixes**
- Enhanced error handling and logging for file loading and directory
access, providing clearer context for issues.

- **Documentation**
- Updated docstrings for functions to improve clarity and detail,
including return type annotations.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

config/ruff.toml

@@ -6,7 +6,7 @@ include = [
   "src/readii/feature_extraction.py",
   "src/readii/cli/**/*.py",
   "src/readii/negative_controls_refactor/**.py",
-  "src/readii/io/writers/**.py",
+  "src/readii/io/**/**.py",
   "src/readii/analyze/**.py"
 ]