update copyright

Author: espdev

click_option_group/__init__.py

@@ -5,7 +5,7 @@
 
 Option groups missing in Click
 
-:copyright: © 2019 by Eugene Prilepin
+:copyright: © 2019-2020 by Eugene Prilepin
 :license: BSD, see LICENSE for more details.
 """
 

docs/conf.py

@@ -22,7 +22,7 @@
 # -- Project information -----------------------------------------------------
 
 project = 'click-option-group'
-copyright = '2020, Eugene Prilepin'
+copyright = '2019-2020, Eugene Prilepin'
 author = 'Eugene Prilepin'
 
 # The full version, including alpha/beta/rc tags