- Update the 'License' tag for the 4.2.0 release.

- Update to 4.2.0:
* See https://krita.org/en/krita-4-2-release-notes/
* Fix: Allow changing layer name to set document as modified
(kde#380437)
* Fix: Allow undoing when changing layer names (kde#380437)
* Fix: Update the undo limit if we change it
* Fix: Handling of modified document notification in sub-window
mode (kde#386488)
* Fix: Fix when holding right-click over layer's color settings
(kde#392815)
* Fix: Do not show language switch warning when going back to the
default (kde#362961)
* Fix: Gradient map color mapping issues (kde#388976)
* Fix: Layout improvements and showing levels for histogram
filter (kde#376048)
* Improvement: Add warning when adding shape to clone layer
(kde#406730)
* Usability: Make default background for text editor white for
readability
* Fix: Activation of FFTW convolution worker (kde#407062)
* Fix: Crash in halftone filter (kde#407045)
* Fix: remove notification for unused keyboard short for
wrap-around (kde#407119)
* Fix: Safe assert triggered while drawing (kde#404552)
* Improvement: Warn artists if they try to render an animated GIF
with over 50 FPS (kde#403873)
* Improvement: Handle calculation better for grayscale images in
high bit depth (kde#405693)