[gnome-builder] gitlabci: Fix submodules init.

[Jordan Petridis <jpetridis src gnome org>]

commit a38accca7af238f6e38d460540aa0c25ee9f8050
Author: Jordan Petridis <jordanpetridis protonmail com>
Date:   Sun Mar 18 06:31:08 2018 +0200

    gitlabci: Fix submodules init.

 .gitlab-ci.yml | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 02790470e..d17472a19 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -5,6 +5,9 @@ flatpak:master:
     image: registry.gitlab.com/alatiera/gnome-nightly-oci/gnome-master:latest
     stage: test
     script:
+    # This should be removed once the base image works with git submodules
+    - dnf install -y git
+
     - flatpak-builder --force-clean --repo=repo app build-aux/flatpak/org.gnome.Builder.json
     - flatpak build-bundle repo builder-dev.flatpak org.gnome.Builder
     artifacts: