Create Redisable#redis (#9633)

* Create Redisable

* Use #redis instead of Redis.current

app/services/follow_service.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class FollowService < BaseService
+  include Redisable
+
   # Follow a remote user, notify remote user about the follow
   # @param [Account] source_account From which to follow
   # @param [String, Account] uri User URI to follow in the form of username@domain (or account record)
@@ -67,10 +69,6 @@ class FollowService < BaseService
     follow
   end
 
-  def redis
-    Redis.current
-  end
-
   def build_follow_request_xml(follow_request)
     OStatus::AtomSerializer.render(OStatus::AtomSerializer.new.follow_request_salmon(follow_request))
   end