[geary] Don't use deprecated Gdk.Pixbuf.new_from_stream_async function.

[Michael Gratton <mjog src gnome org>]

commit f3fd81b8ee560442f45a554224277ce4906d97c4
Author: Michael James Gratton <mike vee net>
Date:   Tue Feb 28 23:23:27 2017 +1100

    Don't use deprecated Gdk.Pixbuf.new_from_stream_async function.

 .../conversation-viewer/conversation-message.vala  |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/client/conversation-viewer/conversation-message.vala 
b/src/client/conversation-viewer/conversation-message.vala
index 7de0fd2..d4be5e6 100644
--- a/src/client/conversation-viewer/conversation-message.vala
+++ b/src/client/conversation-viewer/conversation-message.vala
@@ -658,7 +658,7 @@ public class ConversationMessage : Gtk.Grid {
                                   Cancellable load_cancelled)
     throws Error {
         Gdk.Pixbuf avatar_buf =
-            yield Gdk.Pixbuf.new_from_stream_async(data, load_cancelled);
+            yield new Gdk.Pixbuf.from_stream_async(data, load_cancelled);
 
         if (avatar_buf != null && !load_cancelled.is_cancelled()) {
             int window_scale = get_scale_factor();