Just before release, we added typing for VERSION to be tuple[...],

but I neglected to use an annotations import to ensure this would be

a string on older versions of Python 3.
This change fixes that up so that builds on all supported versions of

Python will complete.

Tested importing buildthings on Python 3.8.
Could not perform a build due to the latest setuptools for Python 3.8

not supporting the new license/license-files configuration.