Add Sidekiq::ServerMiddleware module

https://github.com/sidekiq/sidekiq/blob/f2858e175efd57cffc3db50a19dd315e37b08668/lib/sidekiq/middleware/modules.rb

gems/sidekiq/7.0/_test/test_2.rb

@@ -10,6 +10,7 @@ class Hook
 end
 
 class Middleware
+  include Sidekiq::ServerMiddleware
 end
 
 HardWorker.perform_async(1, 2, 3)

gems/sidekiq/7.0/middleware.rbs

@@ -48,4 +48,14 @@ module Sidekiq
       def initialize: (untyped config, Class klass, *untyped args) -> void
     end
   end
+
+  module ServerMiddleware
+    attr_accessor config: Config
+
+    def redis_pool: () -> ConnectionPool[RedisClientAdapter]
+
+    def logger: () -> Logger
+
+    def redis: () { (RedisClientAdapter::CompatClient) -> void } -> void
+  end
 end