add Daniel Sheeler to copyright in about dialog

diff --git a/jack_mixer.py b/jack_mixer.py
index a5edce4047a0dfd269e25d708eff849329debd60..c1f6a163584415e21300c32462d7cdcb55f07f1a 100755 (executable)
--- a/jack_mixer.py
+++ b/jack_mixer.py
@@ -560,7 +560,7 @@ class JackMixer(SerializedObject):
     def on_about(self, *args):
         about = Gtk.AboutDialog()
         about.set_name('jack_mixer')
-        about.set_copyright('Copyright © 2006-2010\nNedko Arnaudov, Frederic Peters, Arnout Engelen')
+        about.set_copyright('Copyright © 2006-2020\nNedko Arnaudov, Frederic Peters, Arnout Engelen, Daniel Sheeler')
         about.set_license('''\
 jack_mixer is free software; you can redistribute it and/or modify it
 under the terms of the GNU General Public License as published by the