[citemplates] flatpak: nightly publish from `main` and `mainline` branches as well

[Jordan Petridis <jpetridis src gnome org>]

commit 230b093ef38514ef20a5abd744576a8e26de6a9a
Author: Jordan Petridis <jpetridis gnome org>
Date:   Thu Jul 2 16:22:26 2020 +0300

    flatpak: nightly publish from `main` and `mainline` branches as well

 flatpak/flatpak_ci_initiative.yml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/flatpak/flatpak_ci_initiative.yml b/flatpak/flatpak_ci_initiative.yml
index 7a27f13..d839294 100644
--- a/flatpak/flatpak_ci_initiative.yml
+++ b/flatpak/flatpak_ci_initiative.yml
@@ -79,6 +79,8 @@
     FLATPAK_REPO: nightly
   only:
     refs:
-      - master
+      - 'master'
+      - 'main'
+      - 'mainline'
     variables:
       - $REPO_TOKEN