vendor: update buildkit to v0.19.0-rc1

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/golang.org/x/net/websocket/dial.go

@@ -0,0 +1,29 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package websocket
+
+import (
+	"context"
+	"crypto/tls"
+	"net"
+)
+
+func dialWithDialer(ctx context.Context, dialer *net.Dialer, config *Config) (conn net.Conn, err error) {
+	switch config.Location.Scheme {
+	case "ws":
+		conn, err = dialer.DialContext(ctx, "tcp", parseAuthority(config.Location))
+
+	case "wss":
+		tlsDialer := &tls.Dialer{
+			NetDialer: dialer,
+			Config:    config.TlsConfig,
+		}
+
+		conn, err = tlsDialer.DialContext(ctx, "tcp", parseAuthority(config.Location))
+	default:
+		err = ErrBadScheme
+	}
+	return
+}