Revert "Update django from 4.2.11 to 5.0.4"

Django 5 seems to include some sort of inline JavaScript which is
blocked by our Content-Security-Policy and causes the SimpleMDE editor
not to render

This reverts commit 752aa84.

requirements/base.txt

@@ -4,7 +4,7 @@ allpairspy==2.5.1
 bleach==6.1.0
 bleach-allowlist==1.0.3
 defusedxml==0.7.1
-Django==5.0.4
+Django==4.2.11
 django-attachments==1.11
 django-colorfield==0.11.0
 django-contrib-comments==2.2.0