update go.mod

Author: as

go.mod

@@ -14,7 +14,7 @@ require (
 	github.com/as/shiny v0.6.13
 	github.com/as/srv v0.6.8
 	github.com/as/text v0.6.13
-	github.com/as/ui v0.6.14
+	github.com/as/ui v0.6.15
 	github.com/as/worm v0.6.7
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0
 	golang.org/x/image v0.0.0-20180403161127-f315e4403028