Remove duplicate 'cache_store' configuration in test environment

config/environments/test.rb

@@ -7,8 +7,6 @@ Rails.application.configure do
   # and recreated between test runs. Don't rely on the data there!
   config.cache_classes = false
-  config.cache_store = :null_store
-
   # Configure static asset server for tests with Cache-Control for performance
   config.serve_static_files = true
   config.static_cache_control = "public, max-age=3600"