LICENSE: change date in copyright notice

[exercism-bot]

More info: exercism/org-wide-files@abf3f0c

[ee7]

The exercism/org-wide-files thing looks useful.

But I'll set this as draft for now, because this might technically be a bad change. This might be best as (see #198)

Copyright (c) 2014-2019 Exercism, Inc
Copyright (c) 2019-2021 Exercism

or maybe

Copyright (c) 2014 Exercism, Inc
Copyright (c) 2019 Exercism

These seem questionable/bad:

Copyright (c) 2014 Exercism, Inc

Copyright (c) 2014-2021 Exercism

There's an argument that we should only use a date range if every year in that range was a "copyrightable year". It turns out that's okay for this repo, but it's hard to do that generally.

Copyright notices doesn't mean what most people think they mean. See e.g.:

• https://softwareengineering.stackexchange.com/questions/210472/is-renewal-of-mit-license-needed-on-github-at-the-beginning-of-each-year
• https://opensource.stackexchange.com/questions/5778/why-do-licenses-such-as-the-mit-license-specify-a-single-year
• https://writing.kemitchell.com/2016/09/21/MIT-License-Line-by-Line.html

[ee7]

I'll merge this to keep the other org-wide-files commits more atomic. But to be pedantic, this change might violate

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

I think it'd be better if the LICENSE file was just kept in CODEOWNERS, rather than in org-wide-files.