[gdm] configure: update to 3.28.0

[Ray Strode <halfline src gnome org>]

commit a510c612b4646b98167d58a699dbb9b1b95aaa8c
Author: Ray Strode <rstrode redhat com>
Date:   Tue Mar 13 10:01:00 2018 -0400

    configure: update to 3.28.0

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index a3b6265..9c1fdb4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,7 +1,7 @@
 
 AC_PREREQ([2.60])
 AC_INIT([gdm],
-        [3.27.92],
+        [3.28.0],
         [http://bugzilla.gnome.org/enter_bug.cgi?product=gdm])
 
 AC_CONFIG_SRCDIR([daemon/gdm-manager.c])