Add Django 5.1

Author: matthiask

CHANGELOG.rst

@@ -11,6 +11,7 @@ Next version
 - Added automatic scrolling while dragging plugins.
 - Fixed a bug where a plugin with multiple fieldsets wouldn't collapse
   completely.
+- Added Django 5.1 to the CI.
 
 
 7.0 (2024-05-31)

tox.ini

@@ -2,7 +2,7 @@
 envlist =
     py{38,39,310}-dj{32,41}
     py{310,311}-dj{32,41,42,main}
-    py{312}-dj{42,50,main}
+    py{312}-dj{42,50,51,main}
     docs
 
 [testenv]
@@ -16,6 +16,7 @@ deps =
     dj41: Django>=4.1,<4.2
     dj42: Django>=4.2,<5.0
     dj50: Django>=5.0,<5.1
+    dj51: Django>=5.1,<5.2
     djmain: https://github.com/django/django/archive/main.tar.gz
 
 [testenv:docs]