Lower-case request headers.

Author: ioquatix

test/async/http/proxy.rb

@@ -206,7 +206,7 @@
 			end
 
 			with 'request includes headers' do
-				let(:headers) { [['Proxy-Authorization', 'supersecretpassword']] }
+				let(:headers) { [['proxy-authorization', 'supersecretpassword']] }
 
 				it 'succeeds' do
 					endpoint = Async::HTTP::Endpoint.parse("https://www.google.com")