[gimp] (10 commits) Non-fast-forward update to branch wip/nielsdg/gimp-type-rgb-signals

[Jehan <jehanp src gnome org>]

The branch 'wip/nielsdg/gimp-type-rgb-signals' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  e21b514... Use GIMP_TYPE_RGB instead of G_TYPE_POINTER

Commits added to the branch:

  93602a3... Issue #4326 - Add visual tab to spyrogimp plugin (*)
  2baf8a3... gitlab-ci: babl requires now vapigen for Vala binding. (*)
  6cf9bad... gitlab-ci: cppcheck does not need to wait for previous stag (*)
  e0a5aae... Issue #4992 - Modifiers change Free Select tool mode while  (*)
  50d9886... Update Ukrainian translation (*)
  29b1d91... devel-docs: update debugging-tips with GEGL's meson option  (*)
  97fcc8c... gir: Mark gimp_dialog_new() parent nullable (*)
  58fecd7... gir: Make sure the GIR file includes the correct header (*)
  82e945d... Add GIR annotations to bilinear utils (*)
  4729fc8... Use GIMP_TYPE_RGB instead of G_TYPE_POINTER

(*) This commit already existed in another branch; no separate mail sent