Fix font bug in ProgressBox
Summary:
BUG: 391296
Instead of using system's default font, it was using the best suited font which was matching with system's look and feel.
Test Plan:
Before:
After:
Reviewers: sandsmark, ngraham
Reviewed By: sandsmark, ngraham
Subscribers: kde-utils-devel
Differential Revision: https://phabricator.kde.org/D26727