Regenerated requirements.txt with pipreqs

[AndrewPardoe]

Addressing #32.

I regenerated the requirements file using pipreqs. I'm pretty sure this is the minimum requirements set.

I tested by installing a fresh Ubuntu. In order to get the script to run, I had to run the following commands (python3 was already in the base distro):

sudo apt update
sudo apt install python3-pip
sudo apt install python3-ldap
pip3 install -r requirements.txt