graphics/kvantum: update to 0.20.2

V0.20.2
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- Allow opening of the user config file from Kvantum Manager.
- Respect KDE's scrollbar click behavior by default.
- Elide push button text if there isn't enough space for it.
- Better eliding of multiline texts.
- Added LibreOffice to the black list of window dragging (as a workaround for
issues related to its Qt5 skin under Wayland).

(pin)