Fix show_exceptions setting for Rails main (#1920)

* Fix show_exceptions setting for Rails main

* Add changelog entry

Author: camertron

docs/CHANGELOG.md

@@ -10,6 +10,10 @@ nav_order: 5
 
 ## main
 
+* Use correct value for the `config.action_dispatch.show_exceptions` config option for edge Rails.
+
+    *Cameron Dutro*
+
 * Remove unsupported versions of Rails & Ruby from CI matrix.
 
     *Reegan Viljoen*

test/sandbox/config/environments/test.rb

@@ -17,7 +17,7 @@
   config.action_controller.perform_caching = false
 
   # Raise exceptions instead of rendering exception templates
-  config.action_dispatch.show_exceptions = false
+  config.action_dispatch.show_exceptions = (Rails::VERSION::STRING < "7.1") ? false : :none
 
   # Disable request forgery protection in test environment
   config.action_controller.allow_forgery_protection = false