[gnome-calculator] CI: setup UI tests under broadway for GCi

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit bd51a272b88a2b187765c777b49504feee616620
Author: Daniel Espinosa <esodan gmail com>
Date:   Sun Oct 20 17:26:12 2019 -0500

    CI: setup UI tests under broadway for GCi

 .gitlab-ci.yml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index a397785c..59a1710d 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -24,7 +24,8 @@
 .test_template: &meson_test
   stage: test
   script:
-    - ninja -C _build test
+    - broadwayd &
+    - GDK_BACKEND=broadway ninja -C _build test
 
 build:fedora:
   <<: *fedora_before_script