[gitg] packaging: update gtkspell3 dependency

[Alberto Fanjul <albfan src gnome org>]

commit 02453de81c1604fa526bc2ed739d1e2acb6e8051
Author: Gaurav Agrawal <agrawalgaurav1999 gmail com>
Date:   Mon May 20 07:01:14 2019 +0530

    packaging: update gtkspell3 dependency

 PACKAGING | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/PACKAGING b/PACKAGING
index 1cd832db..16363c0d 100644
--- a/PACKAGING
+++ b/PACKAGING
@@ -101,7 +101,7 @@ change and a definite list can be obtained by inspecting configure.ac instead:
 - gsettings-desktop-schemas
 - libpeas >= 1.5.0
 - libpeas-gtk >= 1.5.0
-- gtkspell3 => 3.0.3
+- gtkspell3 >= 3.0.3
 
 gitg has a soft dependency on python due to its plugin system. Building gitg
 without python is perfectly possible, and since there are currently no plugins