Update id/auth

vendor/git.autistici.org/id/auth/client/client.go

 package client
 
 import (
-	"bytes"
 	"context"
-	"io"
 	"net/textproto"
 
 	"git.autistici.org/id/auth"
@@ -47,11 +45,8 @@ func (c *socketClient) Authenticate(ctx context.Context, req *auth.Request) (*au
 	go func() {
 		defer close(done)
 
-		// Write the command to a buffer.
-		var buf bytes.Buffer
-		io.WriteString(&buf, "auth ")
-		buf.Write(c.codec.Encode(req))
-		if err := conn.PrintfLine(buf.String()); err != nil {
+		// Write the auth command to the connection.
+		if err := conn.PrintfLine("auth %s", string(c.codec.Encode(req))); err != nil {
 			done <- err
 			return
 		}

vendor/vendor.json

@@ -27,16 +27,16 @@
 			"revisionTime": "2019-01-29T12:17:45Z"
 		},
 		{
-			"checksumSHA1": "T9WPwUls+LPk89st6TGCbQf5HNQ=",
+			"checksumSHA1": "1glPoZd+eB3t+IpnyIDxEZHybA4=",
 			"path": "git.autistici.org/id/auth",
-			"revision": "b9fd25734d1e2a7f92f32ab982f9c55fd9f9ef24",
-			"revisionTime": "2019-05-04T07:53:15Z"
+			"revision": "865e6264c3f5792d58aa6ba9ed0f37c75fe607c2",
+			"revisionTime": "2019-05-24T11:03:32Z"
 		},
 		{
-			"checksumSHA1": "t3JTZ0bAMQit79HYbcEykC8uxro=",
+			"checksumSHA1": "Xd+uslNbKnbygNAhwAWQ2JVc6do=",
 			"path": "git.autistici.org/id/auth/client",
-			"revision": "b9fd25734d1e2a7f92f32ab982f9c55fd9f9ef24",
-			"revisionTime": "2019-05-04T07:53:15Z"
+			"revision": "865e6264c3f5792d58aa6ba9ed0f37c75fe607c2",
+			"revisionTime": "2019-05-24T11:03:32Z"
 		},
 		{
 			"checksumSHA1": "MlpsZgRytv/c9IX9YawRJDN/ibQ=",