Update tox with django 4.2rc1 (#8920)

Author: auvipy

tox.ini

@@ -21,7 +21,7 @@ deps =
         django32: Django>=3.2,<4.0
         django40: Django>=4.0,<4.1
         django41: Django>=4.1,<4.2
-        django42: Django>=4.2b1,<5.0
+        django42: Django>=4.2rc1,<5.0
         djangomain: https://github.com/django/django/archive/main.tar.gz
         -rrequirements/requirements-testing.txt
         -rrequirements/requirements-optionals.txt