disable tasyncssl on appveyor

tests/async/tasyncssl.nim

@@ -2,6 +2,7 @@ discard """
   file: "tasyncssl.nim"
   cmd: "nim $target --hints:on --define:ssl $options $file"
   output: "500"
+  disabled: "appveyor"
 """
 import asyncdispatch, asyncnet, net, strutils, os