[gnome-games] Revert "dummy-release-date: Return null"

[Alexander Mikhaylenko <alexm src gnome org>]

commit a336dfc621304211b637f9e87adb0cab8ff490f6
Author: Alexander Mikhaylenko <exalm7659 gmail com>
Date:   Mon Oct 8 22:36:34 2018 +0000

    Revert "dummy-release-date: Return null"
    
    This reverts commit d38820fcb068cd4682785e617ef3fd39bf41a480

 src/dummy/dummy-release-date.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/dummy/dummy-release-date.vala b/src/dummy/dummy-release-date.vala
index 2762e39b..895e6842 100644
--- a/src/dummy/dummy-release-date.vala
+++ b/src/dummy/dummy-release-date.vala
@@ -2,6 +2,6 @@
 
 public class Games.DummyReleaseDate : Object, ReleaseDate {
        public DateTime get_release_date () {
-               return null;
+               return new DateTime.utc (1970, 1, 1, 0, 0, 0);
        }
 }