[shotwell] Fix missing ()

[Jens Georg <jensgeorg src gnome org>]

commit f76afd297513a5f516d72aab714afb8d79f0d231
Author: Jens Georg <mail jensge org>
Date:   Mon Mar 18 21:45:41 2019 +0100

    Fix missing ()

 src/AppDirs.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/AppDirs.vala b/src/AppDirs.vala
index 97824577..4d236d71 100644
--- a/src/AppDirs.vala
+++ b/src/AppDirs.vala
@@ -350,7 +350,7 @@ class AppDirs {
 
     public static File get_openface_dnn_dir() {
         var f = File.new_for_path("/app/extra");
-        if (f.query_exists)
+        if (f.query_exists())
             return f;
 
         return get_data_subdir("data"); //get_child("openface.nn4.small2.v1.t7");