increment version number to 0.21.1

NEWS

+ver 0.21.1 (not yet released)
+
 ver 0.21 (2018/10/31)
 * configuration
   - add "include" directive, allows including config files

doc/conf.py

@@ -38,9 +38,9 @@ author = 'Max Kellermann'
 # built documents.
 #
 # The short X.Y version.
-version = '0.21'
+version = '0.21.1'
 # The full version, including alpha/beta/rc tags.
-release = '0.21~git'
+release = version
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.

meson.build

 project(
   'mpd',
   ['c', 'cpp'],
-  version: '0.21',
+  version: '0.21.1',
   meson_version: '>= 0.47',
   default_options: [
     'c_std=c99',