Modify `python` used in `seff-array`

[b-reyes]

We currently use just python in seff-array. This works in our current form because we add a specific python to the path that has the required libraries. However, we do not want to add a specific Python to the path because this could conflict with a user's Python. To get around this, we need to put an explicit path for the python and them remove the addition of Python to the path in the slurmtools module.