Fix build warning of using deprecated API

Girgias · Girgias · commit abb58175610d · 2022-10-10T10:38:49.000+01:00
diff --git a/Book/conf.py b/Book/conf.py
@@ -39,7 +39,7 @@
 
 # Add static stylesheets
 def setup(app):
-    app.add_stylesheet('style.css')
+    app.add_css_file('style.css')
 
 # The suffix of source filenames.
 source_suffix = '.rst'
