Fix black formatting for notebook magic files

Applied black formatting to notebook_magic.py and test_notebook_magic.py
to ensure consistent code style.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: jeremymanning

clustrix/notebook_magic.py

@@ -8,6 +8,7 @@
 import json
 import yaml
 from pathlib import Path
+
 # Type hints would be used if adding type annotations in the future
 import logging
 

tests/test_notebook_magic.py

@@ -15,6 +15,7 @@
     ClusterfyMagics,
     load_ipython_extension,
 )
+
 # Import removed as it's not used directly in tests