Support running CLI arg testing by changingin src/<package_name>/__init__.py

Working content:
```py
"""Contains the project versioning."""

__version__ = "0.0.1"
__version_info__ = tuple(int(i) for i in __version__.split(".") if i.isdigit())

from tui_labeller.__main__ import main

_ = main # Prevents linter warnings without executing `main`.

```