[libchamplain] Post release version bump

[Jiří Techet <jiritechet src gnome org>]

commit b3ff665d46560b8e6e89511f30f4abb39cd485b2
Author: Jiří Techet <techet gmail com>
Date:   Mon Oct 28 15:19:20 2019 -0700

    Post release version bump

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 0b694f0..8c40f52 100644
--- a/meson.build
+++ b/meson.build
@@ -1,6 +1,6 @@
 project(
   'libchamplain', 'c',
-  version: '0.12.20',
+  version: '0.12.21',
   license: 'LGPLv2.1+',
   meson_version: '>= 0.49.0',
   default_options: [