Update dsh revision in Berksfile

Fixed dsh cookbook crash when admin_user was passed as a hash, causing
us to pin to a quite old version of the cookbook.

https://github.com/rcbops-cookbooks/dsh/commit/9e190aaad7db3f2195df1a9e48c7678b89a3c1cf
Merge pull request #130 from claco/update-dsh

Merged automatically by jenkins after successful build test