bump dhrun

pkgs/dhrun/pin.json

 {
   "url": "https://github.com/freuk/dhrun.git",
-  "rev": "2394f237e7187670a528168f923a28ac63d37831",
-  "date": "2019-05-07T06:49:32-05:00",
-  "sha256": "16zz6lys5rvkn9kb9rlqqfv9fsj3k81m4d4nhyg115g1wvijc3r8",
+  "rev": "d776a6f9da9ccaf840f195c38dccb3c60389aca0",
+  "date": "2019-05-16T10:19:10-05:00",
+  "sha256": "0sm5s1nz7n81r6zy7b7k4nkf3pz8rsnw7q8z54sdrx3xvcs4xp91",
   "fetchSubmodules": false
 }