Fix Makefile to use jupyter-book CLI instead of python -m

jupyter-book v1 doesn't support python -m invocation. Use the
jupyter-book CLI command directly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: PavelMakarchuk

Makefile

@@ -1,8 +1,8 @@
 all: install format test build changelog
 
 documentation:
-	python -m jupyter_book clean docs
-	python -m jupyter_book build docs
+	jupyter-book clean docs
+	jupyter-book build docs
 
 format:
 	black . -l 79