It seems git commit ad5b290 is supposed to provide support for GIRepository 2.0, but it fails to work for me on an up-to-date Debian sid system:

-- Checking for module 'gobject-introspection-1.0'
--   Package 'gobject-introspection-1.0' not found

It seems to me that C++ code is adapted but CMake files still require some adaption. I tried simply replacing "1.0" with "2.0" in cmake/FindGObjectIntrospection.cmake but that didn't succeed.