Don't use older buggier versions of AppStream Qt

Summary:
This is not a hard requirement so if a distribution is using older
versions then it won't have the feature, but it also won't crash.

CCBUG: 391468

Reviewers: Plasma, hein

Reviewed By: Plasma, hein

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D15263