Supporting python >= 3.7

[Nick Youngblut]

According to https://github.com/nel-lab/FIOLA/blob/master/setup.py, the package supports Python >= 3.7, but it appears that https://github.com/nel-lab/FIOLA/blob/master/requirements.txt is set so strictly that only Python 3.8 is actually supported, and the setup instructions in the README also suggest this:

git clone https://github.com/nel-lab/FIOLA.git
git clone https://github.com/flatironinstitute/CaImAn.git -b v1.9.13
cd FIOLA
conda create --name fiola python==3.8
conda activate fiola
pip install -r requirements.txt 
pip install -e.
cd ../CaImAn
pip install -e . 

Lastly, there appears to be no CI/CD testing (e.g., via GitHub actions) of various python versions to show that Python >= 3.7 is actually supported.

Given that Python 3.8 is rather old and not supported by some platforms (e.g., Terra-Bio), it would be helpful to include more support for other Python versions.