websocket

check error before GotConn for trace

Check for and report bad protocol in TLSClientConfig.NextProtos (#788)

drop the versions of go that are no longer supported + add 1.18 to ci

Changed the method name UnderlyingConn to NetConn to align the methods names with Go 1.18 standard library (#773)

Add check for Sec-WebSocket-Key header (#752)