[gimp/gimp-2-10] build: .gitlab-ci.yml: add xorgproto package

[Michael Schumacher <schumaml src gnome org>]

commit 92fda7713bbefea643e2234b37eb7019fbdea384
Author: Michael Schumacher <schumaml gmx de>
Date:   Sat Dec 21 17:07:34 2019 +0100

    build: .gitlab-ci.yml: add xorgproto package

 .gitlab-ci.yml | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index ab9ddfb446..ec3b0f4d35 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -155,6 +155,7 @@ gegl-git:
         intltool
         iso-codes
         xorg-server-xvfb
+        xorgproto
 
 .gimp-autotools:
   extends: .gimp-base