Python 3 Status should be noted

[tjstub]

On Python 3 Readiness, filelock shows up as not supporting Python 3, even though the examples are written in Python 3. Python 3 Readiness uses caniusepython3, so it is possible some people might be erroneously holding up their updates waiting for Filelock to show as ready.

Py-filelock should publish its Python 3 status.

[AdorablePotato]

I uploaded the latest version which includes the classifiers to PyPi. I hope this fixes this issue.

-- I'm honestly a little bit surprised and flattered this package is listed there.