Fixed #897 Bumped minimum Python 3.8 version and dependencies

[seanlaw]

Fixes #897

Pull Request Checklist

Below is a simple checklist but please do not hesitate to ask for assistance!

• Fork, clone, and checkout the newest version of the code
• Create a new branch
• Make necessary code changes
• Install black (i.e., python -m pip install black or conda install -c conda-forge black)
• Install flake8 (i.e., python -m pip install flake8 or conda install -c conda-forge flake8)
• Install pytest-cov (i.e., python -m pip install pytest-cov or conda install -c conda-forge pytest-cov)
• Run black . in the root stumpy directory
• Run flake8 . in the root stumpy directory
• Run ./setup.sh && ./test.sh in the root stumpy directory
• Reference a Github issue (and create one if one doesn't already exist)

[seanlaw]

@NimaSarajpoor Please review at your earliest convenience

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (e31ea13) 98.93% compared to head (009374f) 98.93%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #898   +/-   ##
=======================================
  Coverage   98.93%   98.93%           
=======================================
  Files          84       84           
  Lines       14236    14236           
=======================================
  Hits        14084    14084           
  Misses        152      152           

Files Changed	Coverage Δ
setup.py	0.00% <ø> (ø)

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[NimaSarajpoor]

@seanlaw
I am not as meticulous as you here :) I checked the changes in this PR and they look good!

[seanlaw]

@NimaSarajpoor Thanks for reviewing this!