ActionCable: don't allowlist keys passed to the Redis initializer

Support all Redis features without needing to maintain a list of valid options that must stay in sync with the upstream client library.

actioncable/lib/action_cable/subscription_adapter/redis.rb

@@ -5,6 +5,8 @@ require "thread"
 gem "redis", ">= 3", "< 5"
 require "redis"
 
+require "active_support/core_ext/hash/except"
+
 module ActionCable
   module SubscriptionAdapter
     class Redis < Base # :nodoc:
@@ -14,7 +16,7 @@ module ActionCable
       # This is needed, for example, when using Makara proxies for distributed Redis.
       cattr_accessor :redis_connector, default: ->(config) do
         config[:id] ||= "ActionCable-PID-#{$$}"
-        ::Redis.new(config.slice(:url, :host, :port, :db, :password, :id))
+        ::Redis.new(config.except(:adapter, :channel_prefix))
       end
 
       def initialize(*)

actioncable/test/subscription_adapter/redis_test.rb

@@ -34,11 +34,11 @@ class RedisAdapterTest::AlternateConfiguration < RedisAdapterTest
 end
 
 class RedisAdapterTest::Connector < ActionCable::TestCase
-  test "slices url, host, port, db, password and id from config" do
+  test "excludes adapter and channel prefix" do
     config = { url: 1, host: 2, port: 3, db: 4, password: 5, id: "Some custom ID" }
 
     assert_called_with ::Redis, :new, [ config ] do
-      connect config.merge(other: "unrelated", stuff: "here")
+      connect config.merge(adapter: "redis", channel_prefix: "custom")
     end
   end