Added
- Initial release of `pytest-ipynb2`.
- Added support for running tests in Jupyter Notebooks.
- Implemented `Notebook` class for parsing notebooks and extracting code and test cells.
- Added GitHub Actions workflows for CI/CD, including linting, testing, type-checking, and publishing.
- Added `justfile` for common development tasks.
- Configured `pyproject.toml` with project metadata, dependencies, and tool configurations.