[geary/wip/mainline-flatpak] Specify mainline as branch for Flatpak manifest

[Michael Gratton <mjog src gnome org>]

commit 5e5c23f246c1fa9681162a266f7478bf43b16630
Author: Michael Gratton <mike vee net>
Date:   Tue Apr 2 13:08:04 2019 +1100

    Specify mainline as branch for Flatpak manifest
    
    See #324

 org.gnome.Geary.json | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/org.gnome.Geary.json b/org.gnome.Geary.json
index c6a625e7..290c2bcb 100644
--- a/org.gnome.Geary.json
+++ b/org.gnome.Geary.json
@@ -197,8 +197,9 @@
             "builddir": true,
             "sources": [
                 {
-                    "type": "dir",
-                    "path": "."
+                    "type": "git",
+                    "url": "https://gitlab.gnome.org/GNOME/geary.git";,
+                    "branch": "mainline"
                 }
             ]
         }