Set minimum meson_version to 0.63.0

Fixes following warning:
WARNING: Project specifies a minimum meson_version '>= 0.56.0' but uses features which were added in newer versions:
 * 0.63.0: {'Wrap files with diff_files'}

meson.build

@@ -2,7 +2,7 @@ project(
   'mpd',
   ['c', 'cpp'],
   version: '0.24',
-  meson_version: '>= 0.56.0',
+  meson_version: '>= 0.63.0',
   default_options: [
     'c_std=c11',
     'build.c_std=c11',