webkit-gtk: Update to 2.36.8

Changes:
2.36.8
======
- Fix jumpy elements when scrolling GitLab and other web sites.
- Fix WebKitWebView:web-process-terminated signal not being emitted
  for the first web view when sandboxing is enabled.
- Fix hang when opening HTML <select> elements in GTK4 builds.
- Fix kinetic scrolling with elements that use overflow scrolling.
- Fix several crashes and rendering issues.

(leot)