[gitg] Bump libgit2 to 0.27

[Alberto Fanjul <albfan src gnome org>]

commit ff233d154ac814e2da61f1f3cbc6de9e90c0a0c6
Author: Alberto Fanjul <albertofanjul gmail com>
Date:   Thu Nov 1 11:07:08 2018 +0100

    Bump libgit2 to 0.27

 org.gnome.gitg.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/org.gnome.gitg.json b/org.gnome.gitg.json
index 14a56a16..f41437d4 100644
--- a/org.gnome.gitg.json
+++ b/org.gnome.gitg.json
@@ -90,7 +90,7 @@
                 {
                     "type" : "git",
                     "url" : "https://github.com/libgit2/libgit2.git";,
-                    "branch" : "maint/v0.26"
+                    "branch" : "maint/v0.27"
                 }
             ]
         },