[gxml] CI: response yes by default on installation

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 8dc6dde130c154b28bebf3dd746c5c17efc6f8e1
Author: Daniel Espinosa <esodan gmail com>
Date:   Fri Mar 2 11:57:54 2018 -0600

    CI: response yes by default on installation

 .gitlab-ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 52d716a..a9305a3 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -6,7 +6,7 @@ stages:
 
 before_script:
   - apt update
-  - apt install libxml2-dev libglib2.0-dev valac meson
+  - apt-get install -y libxml2-dev libglib2.0-dev valac meson
 
 build-gxml:
   stage: build