Specifiy GObject Introspect library versions

Created by: SunilMohanAdapa

I see the following warnings in Plinth with latest libraries. It appears we need to specify the minimum required library version before importing a library using GObject introspection.

Plinth/plinth/package.py:26: PyGIWarning: PackageKitGlib was imported without specifying a version first. Use gi.require_version('PackageKitGlib', '1.0') before import to ensure that the right version gets loaded.
  from gi.repository import PackageKitGlib as packagekit