Fix version range for Django 6.0

Author: michael-k

tox.ini

@@ -18,7 +18,7 @@ setenv =
        PYTHONDONTWRITEBYTECODE=1
 deps =
     django52: Django>=5.2,<6.0
-    django60: Django>=6.0a1,<7.0
+    django60: Django>=6.0a1,<6.1
     !latest: djangorestframework
     latest: {[latest]deps}
     -r requirements/test-ci.txt