[jhbuild] world: Geary has renamed its master branch to mainline

[Ting-Wei Lan <lantw src gnome org>]

commit f5810320fb880fe675e9def361746252b2c30ce0
Author: Ting-Wei Lan <lantw src gnome org>
Date:   Sat Jun 22 23:31:48 2019 +0800

    world: Geary has renamed its master branch to mainline

 modulesets/gnome-world.modules | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/modulesets/gnome-world.modules b/modulesets/gnome-world.modules
index 1cb73a40..22d681a9 100644
--- a/modulesets/gnome-world.modules
+++ b/modulesets/gnome-world.modules
@@ -255,7 +255,7 @@
   </autotools>
 
   <meson id="geary">
-    <branch/>
+    <branch revision="mainline"/>
     <dependencies>
       <dep package="glib"/>
       <dep package="gmime"/>