editors/featherpad: update to 1.3.5

V1.3.5
---------
- Used QPointer for TextEdit's highlighter (for a more robust code but without
  behavior change).
- Enabled tab DND under Wayland (by detaching or dropping the tab after
  finishing the DND) and improved tab DND in general.
- Always open a group of files in a single window, even when the app is
  configured to open files in separate windows.
- Prevented total item deselection in the side-pane mode with Qt6.
- Added the side-pane and session actions to the toolbar.
- Limited the side-pane's default width to 40 times the width of the space
  character of the widget font.

(pin)