Remove obsolete import

src/sync/update-stream.js

@@ -2,7 +2,6 @@
 
 const Promise = require("bluebird");
 const bhttp = require("bhttp");
-const asBuffer = require("as-buffer");
 
 const pipe = require("@promistream/pipe");
 const simpleSource = require("@promistream/simple-source");