fix: Fix Rack > 3.0.0 support

Now Rack::Handler has been moved to a seperate gem, we need to specify
it specifically. I’ve monkeypatched `Rack::Handler::WEBrick` to support
both use cases everywhere in the gem

lib/pact/consumer/server.rb

@@ -1,6 +1,7 @@
 require 'uri'
 require 'net/http'
 require 'rack'
+require 'rack/handler/webbrick'
 
 # Copied shamelessly from Capybara
 # Used to run a mock service in a new thread when started by the AppManager or the ControlServer
@@ -66,11 +67,6 @@ def responsive?
     end
 
     def run_default_server(app, port)
-      begin
-        require 'rack/handler/webrick'
-      rescue LoadError
-        require 'rackup/handler/webrick'
-      end
       Rack::Handler::WEBrick.run(app, **webrick_opts) do |server|
         @port = server[:Port]
       end

lib/pact/mock_service/control_server/run.rb

@@ -1,5 +1,6 @@
 require 'pact/mock_service/control_server/app'
 require 'pact/mock_service/server/webrick_request_monkeypatch'
+require 'rack/handler/webbrick'
 
 module Pact
   module MockService

lib/pact/mock_service/run.rb

@@ -5,6 +5,7 @@
 require 'pact/mock_service/server/webrick_request_monkeypatch'
 require 'pact/specification_version'
 require 'pact/support/metrics'
+require 'rack/handler/webbrick'
 
 module Pact
   module MockService

lib/rack/handler/webbrick.rb

@@ -0,0 +1,12 @@
+module Rack
+  module Handler
+      begin
+        require 'rack/handler/webrick'
+        WEBrick = Class.new(Rack::Handler::WEBrick)
+      rescue LoadError
+        require 'rackup/handler/webrick'
+        WEBrick = Class.new(Rackup::Handler::WEBrick)
+      end
+  end
+end
+