Updated files for 2.1.2 release

Author: kmvanbrunt

.github/CONTRIBUTING.md

@@ -579,6 +579,7 @@ mostly automated. The manual steps are all git operations. Here's the checklist:
 
 1. Make sure you're on the proper branch (almost always **master**)
 1. Make sure all the unit tests pass with `invoke pytest` or `py.test`
+1. Make sure latest year in `LICENSE` matches current year
 1. Make sure `CHANGELOG.md` describes the version and has the correct release date
 1. Add a git tag representing the version number using ``invoke tag x.y.z`` 
     * Where x, y, and z are all small non-negative integers

CHANGELOG.md

@@ -1,4 +1,4 @@
-## 2.1.2 (TBD, 2021)
+## 2.1.2 (July 5, 2021)
 * Enhancements
     * Added the following accessor methods for cmd2-specific attributes to the `argparse.Action` class
         * `get_choices_callable()`
@@ -10,7 +10,6 @@
         * `set_nargs_range()`
         * `get_suppress_tab_hint()`
         * `set_suppress_tab_hint()`
-    
 * Deprecations
     * Now that `set_choices_provider()` and `set_completer()` have been added as methods to the
       `argparse.Action` class, the standalone functions of the same name will be removed in version

LICENSE

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2008-2020 Catherine Devlin and others
+Copyright (c) 2008-2021 Catherine Devlin and others
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal