Replace Async::IO::Socket usage with stdlib Socket for async-http adapter to remove implicit dependency on async-io

Author: jakeonfire

lib/webmock/http_lib_adapters/async_http_client_adapter.rb

@@ -154,9 +154,9 @@ def inspect
 
         def create_connected_sockets
           pair = begin
-            Async::IO::Socket.pair(Socket::AF_UNIX, Socket::SOCK_STREAM)
+            Socket.pair(Socket::AF_UNIX, Socket::SOCK_STREAM)
           rescue Errno::EAFNOSUPPORT
-            Async::IO::Socket.pair(Socket::AF_INET, Socket::SOCK_STREAM)
+            Socket.pair(Socket::AF_INET, Socket::SOCK_STREAM)
           end
           pair.tap do |sockets|
             sockets.each do |socket|

spec/acceptance/async_http_client/async_http_client_spec_helper.rb

@@ -1,3 +1,5 @@
+require "ostruct"
+
 module AsyncHttpClientSpecHelper
   def http_request(method, url, options = {}, &block)
     endpoint = Async::HTTP::Endpoint.parse(url)