[gthumb] set version to 3.9.0

[Paolo Bacchilega <paobac src gnome org>]

commit d29142c46643bce91cf5a2fc0ed774e6262b4254
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Wed Nov 20 11:33:06 2019 +0100

    set version to 3.9.0

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 2566d2a8..77730bae 100644
--- a/meson.build
+++ b/meson.build
@@ -1,6 +1,6 @@
 project('gthumb', ['c', 'cpp'],
   license : 'GPL2+',
-  version : '3.8.2',
+  version : '3.9.0',
   meson_version : '>=0.43'
 )