Merge pull request #468 from koic/fix_hash_except_ruby_2_7

Fix a `NoMethodError` on Ruby 2.7 caused by `Hash#except`

Rakefile

@@ -30,7 +30,7 @@ task :conformance do |t|
   options[:verbose] = true if ENV["VERBOSE"]
 
   Conformance::ServerRunner.new(**options).run
-  Conformance::ClientRunner.new(**options.except(:port)).run
+  Conformance::ClientRunner.new(**options.reject { |key, _value| key == :port }).run
 end
 
 desc "List available conformance scenarios"