example server: do not delay closing socket on goaway frame

this causes the truffleruby build to fail, as it expects to either receive a ping ack or have the connection closed

Author: HoneyryderChuck

example/server.rb

@@ -62,10 +62,7 @@
   end
 
   conn.on(:goaway) do
-    Thread.start do
-      sleep(1)
-      sock.close
-    end
+    sock.close
   end
 
   conn.on(:stream) do |stream|