Specify Python compatibility requirements

[thundergolfer]

Description

Our code uses f-strings which are only available in >= Python 3.6. We should remove them or at least specify in the README that we don't support <= 3.5

[dillon-giacoppo]

Python 3.5 is not EOL until September 13 2020 (https://devguide.python.org/#status-of-python-branches). I think it makes sense to support the oldest supported release of Python. I think the correct approach is to remove the f-strings.

I think its worth stating in the README that supported versions are 3.5+

[thundergolfer]

Agreed.

[dillon-giacoppo]

Fixed in 0.1.2