Update vendored utls

vendor/github.com/refraction-networking/utls/README.md

@@ -1,4 +1,4 @@
-# uTLS
+# ![uTLS](logo_small.png) uTLS
 [![Build Status](https://travis-ci.org/refraction-networking/utls.svg?branch=master)](https://travis-ci.org/refraction-networking/utls)
 [![godoc](https://img.shields.io/badge/godoc-reference-blue.svg)](https://godoc.org/github.com/refraction-networking/utls#UConn)
 ---

vendor/vendor.json

@@ -454,10 +454,10 @@
 			"tree": true
 		},
 		{
-			"checksumSHA1": "Uuafl1PrU6CwsKq6X5ckHNMAA6w=",
+			"checksumSHA1": "Il2hg75p7bPMnE2oEOWo2O8dM4U=",
 			"path": "github.com/refraction-networking/utls",
-			"revision": "b7c656eec2d2aa957b1e844446e867a567e17d1f",
-			"revisionTime": "2019-03-27T16:53:10Z"
+			"revision": "32987941ebd3f6bdd72b521222b4ec5542dff1d0",
+			"revisionTime": "2019-04-15T19:36:40Z"
 		},
 		{
 			"checksumSHA1": "Fn9JW8u40ABN9Uc9wuvquuyOB+8=",