[gnome-continuous] Update the base Yocto branch

[Emmanuele Bassi <ebassi src gnome org>]

commit 0a5614754ffeeb8796fba79e6d64e2d74d895d60
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Sun Mar 18 18:54:13 2018 +0000

    Update the base Yocto branch
    
    Attempt at using the 3.28-rocko branch, which contains a much more up to
    date base system.

 manifest.json |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/manifest.json b/manifest.json
index 16970e1..1d769d5 100644
--- a/manifest.json
+++ b/manifest.json
@@ -7,7 +7,7 @@
   "base": {
             "name": "yocto",
            "src": "gnome:gnome-continuous-yocto",
-            "branch": "gnomeostree-3.22-krogoth"
+            "branch": "gnomeostree-3.28-rocko"
           },
 
   "config-opts": [],