Add git diff content on relint check

[anapaulagomes]

Usage: git diff | relint my_file.py --diff

[codingjoe]

This is really good work @anapaulagomes thanks!

I left you a couple small comments and suggestions.

[codingjoe]

I would recommend to take a look at pycodestyles implementation.
https://github.com/PyCQA/pycodestyle/blob/77ad77278d04db396fcaddbc174b75bf3933a153/pycodestyle.py#L1739-L1765

I would also suggest to parse the diff from stdin and not call a subprocess. This allows people to send any kind of diff to relint. This limits the use case to a pre commit hook.

[codingjoe]

In case you missed it during our 1on1 review: I believe you outdid yourself here. This is really amazing work. You perfectly nailed every single bit. It easily understandable code while not wasting an ounce of memory. 🥇

Are you sure you want to raise the bar that high ;)

[anapaulagomes]

Thank you for your valuable inputs, @codingjoe. 👍🏽

[codingjoe]

perfect, thanks @anapaulagomes

[codingjoe]

Released in 0.4.0