Upgrade bakerydemo to Django 6.0 (#594)

requirements/base.txt

@@ -1,4 +1,4 @@
-Django>=5.2,<5.3
+Django>=6.0,<6.1
 django-dotenv==1.4.2
 wagtail>=7.2,<7.3
 wagtail-font-awesome-svg>=1,<2