Failed to download the package from https://github.com/fsitok/klayout-simplify/tags/0.1.2.
There needs to be a file called 'grain.xml' below this URL. It needs to have the XML format of a KLayout package definition file.
This URL will be used for the package file: https://github.com/fsitok/klayout-simplify/tags/0.1.2/grain.xml.