PS: Remove tox from requirements-dev.txt. See attached screenshot for reference

I don't think that's necessary.

Nothing in the repository refers to requirements-dev.txt, I believe it's for developers' convenience only, in which case pip install -r requirements-dev.txt && tox is a sensible workflow.

I am following the consensus agreed to in pypa/setuptools#931

tox doesn't seem to add any value whatsover even in dev and infact is not recommended for linux python environments (See: pypa/setuptools#931 (comment)
It's not used anywhere so if you are removing it from setup.py, it makes sense you remove it from requirements-dev.txt as well as it will substantially reduce the dependency tree and also for the sake of consistency and brevity.

Having said that, I don't have any problem if the contributers or members agree to keeping tox. Maybe removing tox from requirements-dev in a separate PR after this commit is merged would be wiser?