fix: fix Ruby 2.7 kwargs warning (pact-foundation#122)

Author: barthez

lib/pact/consumer/server.rb

@@ -67,7 +67,7 @@ def responsive?
 
     def run_default_server(app, port)
       require 'rack/handler/webrick'
-      Rack::Handler::WEBrick.run(app, webrick_opts) do |server|
+      Rack::Handler::WEBrick.run(app, **webrick_opts) do |server|
         @port = server[:Port]
       end
     end

lib/pact/mock_service/control_server/run.rb

@@ -24,7 +24,7 @@ def call
           # server, and can't shut it down. So, keep a manual reference to the Webrick server, and
           # shut it down directly rather than use Rack::Handler::WEBrick.shutdown
           # Ruby!
-          Rack::Handler::WEBrick.run(control_server, webbrick_opts) do | server |
+          Rack::Handler::WEBrick.run(control_server, **webbrick_opts) do | server |
             @webrick_server = server
           end
         end

lib/pact/mock_service/run.rb

@@ -25,7 +25,7 @@ def call
 
         require_monkeypatch
 
-        Rack::Handler::WEBrick.run(mock_service, webbrick_opts)
+        Rack::Handler::WEBrick.run(mock_service, **webbrick_opts)
       end
 
       private