Allow middleware to yield arguments (#4673)

The arguments are always ignored, but this allows the block to be passed
to a method that yields arguments:

    class TaggedLoggingMiddleware
      def call(*, &block)
        Rails.logger.tagged("my cool job", &block)
      end
    end

Changes.md

@@ -6,6 +6,7 @@ HEAD
 ---------
 
 - Fix Web UI crash with corrupt session [#4672]
+- Allow middleware to yield arguments [#4673, @eugeneius]
 
 6.1.1
 ---------

lib/sidekiq/middleware/chain.rb

@@ -133,7 +133,7 @@ module Sidekiq
         return yield if empty?
 
         chain = retrieve.dup
-        traverse_chain = lambda do
+        traverse_chain = proc do
           if chain.empty?
             yield
           else

test/test_middleware.rb

@@ -41,6 +41,12 @@ describe Sidekiq::Middleware do
     end
   end
 
+  class ArgumentYieldingMiddleware
+    def call(*args)
+      yield 1
+    end
+  end
+
   class AnotherCustomMiddleware
     def initialize(name, recorder)
       @name = name
@@ -113,6 +119,15 @@ describe Sidekiq::Middleware do
     assert_equal [], recorder
   end
 
+  it 'allows middleware to yield arguments' do
+    chain = Sidekiq::Middleware::Chain.new
+    chain.add ArgumentYieldingMiddleware
+
+    final_action = nil
+    chain.invoke { final_action = true }
+    assert_equal true, final_action
+  end
+
   describe 'I18n' do
     before do
       require 'i18n'