This is a follow-up to commit 26876b66001a1dc45ee6d05015fddd7f5a88676e,
migrate the package from Python 2 to Python 3 (but left some commented inputs
for tests, breaking the build).
* gnu/packages/display-managers.scm (lightdm)[native-inputs]: Un-comment
python-wrapper and python-pygobject.
68db023498