Failed to download the package from https%3A%2F%2Fgithub.com%2Fklayoutmatthias%2Fxsection.git%2Ftags%2F1.3%2Fsrc.
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%3A%2F%2Fgithub.com%2Fklayoutmatthias%2Fxsection.git%2Ftags%2F1.3%2Fsrc/grain.xml.