[gnome-themes-extra/gitlab-ci] CI: Install GTK+ 2

[Juraj Fiala <jurf src gnome org>]

commit ee2dcadb5504b8432bef2ce6b951285e07b70337
Author: Juraj Fiala <jurf riseup net>
Date:   Fri Mar 2 11:56:26 2018 +0000

    CI: Install GTK+ 2

 .gitlab-ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 9d09380f..5752d401 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -9,7 +9,7 @@ build:
   # instead of calling g++ directly you can also use some build toolkit like make
   # install the necessary build tools when needed
   before_script: 
-    - apt update && apt -y install make autoconf gnome-common
+    - apt update && apt -y install make autoconf gnome-common gtk+2.0
   script: 
     - ./autogen.sh --disable-gtk3-engine
     - make