Pillow python dependency provided for NIX

[WonderBeat]

QMK requires pillow python dependency, but NIX project definition lacks of it

Description

Project requires python pillow and requirements.txt contains this dependency. But NIX project definition file doesn't.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[sigprof]

Already fixed by #17243 (and the fix is already in the master branch).

(Also changing just pyproject.toml is not enough — as a minimum, poetry.lock needs to be updated, and in this particular case more updates are needed to make things actually build properly, which you can find in that PR.)