Make the README mention our Django>=3.2.4 requirement

Author: matthiask

README.rst

@@ -45,7 +45,7 @@ In addition to the built-in panels, a number of third-party panels are
 contributed by the community.
 
 The current stable version of the Debug Toolbar is 3.5.0. It works on
-Django ≥ 3.2.
+Django ≥ 3.2.4.
 
 Documentation, including installation and configuration instructions, is
 available at https://django-debug-toolbar.readthedocs.io/.