v5.1.0

• Possible breaking change: Loading variables from a .env file is only supported when installed using the dotenv extra (pip install sys-vars[dotenv])
• Improve function signatures by explicitly adding a default parameter instead of using kwargs
• Add backtics to Python methods and types in function docstrings to indicate code elements
• Include py.typed file in wheel
• Replace black with ruff

Full Changelog: v5.0.0...v5.1.0