Added ability to set directory in pytorch lightning

[fishbotics]

As its currently implemented, there's no great way to set the directory for the keepsake logs as it's hardcoded as "."

This makes it so that passing in a filepath with actually lead to the path being used, both for the directory and also for the specifickeepsake file.

[fishbotics]

When I run black --check keepsake/pl_callback.py in my local repo it passes. Maybe I'm using the wrong version of black? Or the wrong version of Python?

How should I change this to pass muster?