[gnome-runtime-images] build: pass --format=docker to buildah bud

[Jordan Petridis <jpetridis src gnome org>]

commit 8e03908bfd12d8f84494494cf44f079c6206853f
Author: Jordan Petridis <jpetridis gnome org>
Date:   Fri Aug 9 11:51:43 2019 +0000

    build: pass --format=docker to buildah bud
    
    Docker is eating my soul. Send halp.
    
    https://github.com/containers/buildah/issues/575

 .gitlab-ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index b190e0d..ef86e84 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -17,7 +17,7 @@ stages:
         - echo ${DOCKERFILE} / ${DOCKERIMAGE}
         - dnf install -y buildah podman
         - buildah login -u gitlab-ci-token -p ${CI_JOB_TOKEN} ${CI_REGISTRY}
-        - buildah bud --pull -f ${DOCKERFILE} -t ${DOCKERIMAGE} .
+        - buildah bud --format=docker --pull -f ${DOCKERFILE} -t ${DOCKERIMAGE} .
         - buildah push ${DOCKERIMAGE}
     after_script:
         # don't try to use systemd/journald