Removed unused imports from all python files

[jhoshiko]

This PR removes all unused imports from the python files using VSCode and Flake8 to identify imports that are unused. I ran the simulation and didn't notice any issues, but please test this branch on your end and let me know if you have any concerns!

Closes #6

[lijiyao919]

could you remove out the last line in simulate.py: os.chown(output_fname, uid, gid)?

Have you pass the run? (refer to the run command in issue#2)

[jhoshiko]

@lijiyao919 I can yeah. Looks like we've ran into this issue before as documented in the windows installation instructions:

Use code 'python -u simulate.py -c -cf custom -l -r 06197001' in command prompt to run the project.
AttributeError: module 'os' has no attribute 'chown' will be given but the result file 'model_data_{year}.h5' will still be obatined.

I did run into this attribute error while running but it looks like I'm still getting outputs.

[lijiyao919]

looks good.