Update copyright notice
Update copyright notice

Since we are updating PyScaffold's license, I thought about updating the
copyright notice also to reflect the current situation of the project.

The main inspiration comes from projects like:

- https://github.com/ponylang/ponyc/blob/main/LICENSE
- https://github.com/Homebrew/brew/blob/master/LICENSE.txt

Alternatively we could also do like NetBeans does:

- https://github.com/apache/netbeans/blob/master/NOTICE

blue-yonder/pyscaffold,blue-yonder/pyscaffold