[citemplates/wip/mjog/flatpak-xvfb-socket] Fix tests being unable to access X11 display server

[Michael Gratton <mjog src gnome org>]

commit f122a4287c64c6108dc25de0cb92e94bcbbe80a7
Author: Michael Gratton <mike vee net>
Date:   Mon Jan 21 13:26:19 2019 +1030

    Fix tests being unable to access X11 display server

 flatpak/flatpak_ci_initiative.yml | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/flatpak/flatpak_ci_initiative.yml b/flatpak/flatpak_ci_initiative.yml
index 452143a..b818b47 100644
--- a/flatpak/flatpak_ci_initiative.yml
+++ b/flatpak/flatpak_ci_initiative.yml
@@ -14,6 +14,7 @@
       flatpak build
       --env=LANG=C.UTF-8
       --env=NO_AT_BRIDGE=1
+      --socket=x11
       app
       dbus-run-session
       meson test -C _build --no-stdsplit --print-errorlogs