Replace black with ruff formatter about skeleton

[bswck]

Based! 🚀

[jaraco]

While rolling this out, I've learned that the removal of the black badge triggers merge conflicts due to changes in the subsequent RTD badge (when it's been enabled downstream). The jaraco.develop routine that resolves the conflict ends up discarding the downstream change (causing the RTD badge to be commented out again if it had been uncommented).

[jaraco]

This is what the conflict looks like unresolved:

 path main @ git diff
diff --cc README.rst
index c8f71e1,2fabcf3..0000000
--- a/README.rst
+++ b/README.rst
@@@ -11,12 -11,8 +11,17 @@@
      :target: https://github.com/astral-sh/ruff
      :alt: Ruff
  
++<<<<<<< HEAD
 +.. image:: https://img.shields.io/badge/code%20style-black-000000.svg
 +   :target: https://github.com/psf/black
 +   :alt: Code style: Black
 +
 +.. image:: https://readthedocs.org/projects/path/badge/?version=latest
 +   :target: https://path.readthedocs.io/en/latest/?badge=latest
++=======
+ .. .. image:: https://readthedocs.org/projects/PROJECT_RTD/badge/?version=latest
+ ..    :target: https://PROJECT_RTD.readthedocs.io/en/latest/?badge=latest
++>>>>>>> b8c6c1530ef937521b60aabb0ecd98a8b5dca761
  
  .. image:: https://img.shields.io/badge/skeleton-2023-informational
     :target: https://blog.jaraco.com/skeleton