[gnome-calendar] Bump meson version to 0.50.0

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 2e5067d75c83bbb39802d0abf3530a893f8e247c
Author: Ömer Fadıl USTA <omerusta gmail com>
Date:   Sat Jul 6 08:36:02 2019 +0300

    Bump meson version to 0.50.0

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index db2b68ea..e9864744 100644
--- a/meson.build
+++ b/meson.build
@@ -3,7 +3,7 @@ project(
                'c',
            version: '3.33.1',
            license: 'GPL3+',
-     meson_version: '>= 0.42.0'
+     meson_version: '>= 0.50.0'
 )