Fix Delegator to pass keyword arguments for Ruby 3.0

lib/sinatra/base.rb

@@ -1947,6 +1947,8 @@ def self.delegate(*methods)
           return super(*args, &block) if respond_to? method_name
           Delegator.target.send(method_name, *args, &block)
         end
+        # ensure keyword argument passing is compatible with ruby >= 2.7
+        ruby2_keywords(method_name) if respond_to?(:ruby2_keywords, true)
         private method_name
       end
     end

test/delegator_test.rb

@@ -88,6 +88,17 @@ def target
     assert_equal '', response.body
   end
 
+  it "delegates before with keyword arguments correctly" do
+    delegation_app do
+      set(:foo) do |something|
+        something
+      end
+      before(foo: 'bar') do
+        :nothing
+      end
+    end
+  end
+
   it "registers extensions with the delegation target" do
     app, mixin = mirror, Module.new
     Sinatra.register mixin