Fix deprecation warning regarding to_time

We had a deprecation warning: to_time will always preserve
the receive timezone rather than system local time in Rails 8.1
which gets fixed by setting "to_time_preserves_timezone" to "zone"
in the application configuration.

spec/example_app/config/application.rb

@@ -27,6 +27,7 @@ class Application < Rails::Application
 
     config.action_controller.action_on_unpermitted_parameters = :raise
     config.active_record.time_zone_aware_types = %i[datetime time]
+    config.active_support.to_time_preserves_timezone = :zone
 
     # Opt-out of FLoC: https://amifloced.org/
     config.action_dispatch