More linting

[joaonc]

Add more linting tools:

• isort
• black
• flake8
• mypy
• security
• bandit

Note:
Adding these linters will make significant changes to the code. This will make it harder to merge back to the original project pprintpp by the original author.
The benefits are more standardized coding, early bug catching and more security. To me, that's an acceptable trade-off.
If merge to original project is required, we should add the same linters in the code there.

[joaonc]

The 3 PRs above complete this ticket. Closing.