pyproject: Drop Jupyter Notebook.

This is no longer used.

Author: laurensvalk

.gitattributes

@@ -1,5 +1,3 @@
 * text eol=lf
 *.dll binary
 *.exe binary
-*.ipynb filter=nbstripout
-*.ipynb diff=ipynb

.gitignore

@@ -60,9 +60,6 @@ genrst/
 # Temporary files
 demo/_*.py
 
-# Jupyter Notebook
-.ipynb_checkpoints
-
 # Coveage
 .coverage
 coverage.*