[babl] ci: Add GObject introspection packages

[Øyvind "pippin" Kolås <ok src gnome org>]

commit ef4e36d5cf4505e51af9729339ce48dbca908b2a
Author: Niels De Graef <nielsdegraef gmail com>
Date:   Mon Aug 5 22:09:21 2019 +0200

    ci: Add GObject introspection packages
    
    We added GObject introspection in the previous commits, so we need to
    make sure the correct binaries are installed for this.

 .gitlab-ci.yml | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 61eb2eb48..ded277426 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -9,6 +9,7 @@ cache:
     - pacman -Syu --noconfirm --needed --cachedir `pwd`/_pacman_cache
         base-devel
         git
+        gobject-introspection
         ${EXTRA_PKGS}
 
 .meson-build: