[gxml] CI: install gettext dependency

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit ce3957a9055b4daa9d81a6058b54cb6d3898396e
Author: Daniel Espinosa <esodan gmail com>
Date:   Fri Mar 2 12:04:21 2018 -0600

    CI: install gettext dependency

 .gitlab-ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index a774cc1..547ecb3 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -6,7 +6,7 @@ stages:
 
 before_script:
   - apt update
-  - apt-get install -y libxml2-dev libglib2.0-dev valac libgee-0.8-dev meson
+  - apt-get install -y libxml2-dev libglib2.0-dev valac libgee-0.8-dev gettext meson
 
 build-gxml:
   stage: build