[gnome-builder] valgrind: fix missing import

[Christian Hergert <chergert src gnome org>]

commit a8f925794618bfa02ffad34cf70eecd61fbe41cb
Author: Christian Hergert <chergert redhat com>
Date:   Fri Jul 26 23:52:33 2019 -0700

    valgrind: fix missing import
    
    Fixes #990

 src/plugins/valgrind/valgrind_plugin.py | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/plugins/valgrind/valgrind_plugin.py b/src/plugins/valgrind/valgrind_plugin.py
index 67fbf8f75..cb68277ac 100644
--- a/src/plugins/valgrind/valgrind_plugin.py
+++ b/src/plugins/valgrind/valgrind_plugin.py
@@ -21,6 +21,7 @@ import gi
 import os
 
 from gi.repository import Ide
+from gi.repository import Gio
 from gi.repository import GLib
 from gi.repository import GObject