[devhelp] build: require meson >= 0.50

[Sébastien Wilmet <swilmet src gnome org>]

commit 48b158a5d99806de4f21040aa4cac29d5f853850
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Mon Nov 11 11:26:35 2019 +0100

    build: require meson >= 0.50
    
    To fix this warning:
    
    WARNING: Project specifies a minimum meson_version '>= 0.47' but uses
    features which were added in newer versions:
     * 0.50.0: {'install arg in configure_file'}

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 55987a87..3229081e 100644
--- a/meson.build
+++ b/meson.build
@@ -5,7 +5,7 @@
 
 project(
   'devhelp', 'c',
-  meson_version : '>= 0.47',
+  meson_version : '>= 0.50',
   version : '3.34.0',
   default_options : ['warning_level=2']
 )