[amtk] meson: fix version number

[Sébastien Wilmet <swilmet src gnome org>]

commit 4d11753217ac76512c8c0673476073838d7795a2
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Mon Sep 28 20:12:29 2020 +0200

    meson: fix version number
    
    The meson files and the autotools files were not in sync after rebasing
    and merging the meson branch.

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index fe41367..d650a26 100644
--- a/meson.build
+++ b/meson.build
@@ -6,7 +6,7 @@
 project(
   'amtk', 'c',
   meson_version: '>= 0.53',
-  version: '5.1.2',
+  version: '5.2.0',
   default_options: ['warning_level=2']
 )