Fix using .with on composite relations (fix #691)

lib/rom/pipeline.rb

@@ -81,12 +81,18 @@ def method_missing(name, *args, &block)
  # Base composite class with left-to-right pipeline behavior
  #
  # @api private
- class Composite
- (Kernel.private_instance_methods - %i[respond_to_missing? block_given?])
- .each(&method(:undef_method))
+ class Composite < ::BasicObject
+ %i[block_given?].each do |method|
+ define_method(method, ::Kernel.instance_method(method))
+ private method
+ end
+
+ %i[class to_s inspect is_a? instance_of? to_enum].each do |method|
+ define_method(method, ::Kernel.instance_method(method))
+ end
 
- include Dry::Equalizer(:left, :right)
- include Proxy
+ include ::Dry::Equalizer(:left, :right)
+ include ::ROM::Pipeline::Proxy
 
  # @api private
  attr_reader :left