Log Message:
graphics/kvantum: update to 1.0.1

The main reason for this release was that KF5 had a backward incompatible
change. The minimum required version of Qt is bumped to 5.15.0 and that of
KF5 to 5.82.0. As a result, old distros can't be supported anymore.

Other changes:
- A workaround is added for the wrong style code of KisDoubleSliderSpinBox in
  Krita ≥ 5.0.0.
- Options are added (to Kvantum Manager) for setting corner radii when blurring
  translucent menus and tooltips with rounded corners. Usually, a value of 2 is
  enough for preventing blur artifacts.
- 16px is given to the width of vertical spinbox buttons.
- Small fixes.