[gnome-control-center] CI: cache flatpak-builder files

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit ad0f3f6ffb0970780576bc55c70369e8d84578b5
Author: Claudio André <claudioandre br gmail com>
Date:   Thu May 17 12:17:10 2018 -0300

    CI: cache flatpak-builder files
    
    It is needed to make things faster.

 .gitlab-ci.yml | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 108751a49..fd77b5792 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -110,6 +110,10 @@ packaging:
     - flatpak-builder --bundle-sources --repo=devel build ${MANIFEST_PATH}
     - flatpak build-bundle devel ${BUNDLE} --runtime-repo=${RUNTIME_REPO} ${APPID}
 
+  cache:
+    paths:
+    - .flatpak-builder/cache
+
   environment:
     name: review/$CI_COMMIT_REF_NAME
     url: https://gitlab.gnome.org/$CI_PROJECT_PATH/-/jobs/$CI_JOB_ID/artifacts/raw/${BUNDLE}