RedisCacheStore: update test suite for redis-rb 5.0

No real code change, only our stubs need to be changed.

activesupport/test/cache/stores/redis_cache_store_test.rb

@@ -323,13 +323,13 @@ class StoreAPITest < StoreTest
   end
 
   class UnavailableRedisClient < Redis::Client
-    def ensure_connected
+    def ensure_connected(...)
       raise Redis::BaseConnectionError
     end
   end
 
   class MaxClientsReachedRedisClient < Redis::Client
-    def ensure_connected
+    def ensure_connected(...)
       raise Redis::CommandError
     end
   end