Update setup.py, add pyproject.toml and use setup.cfg for metadata also remove unncecesary files

[LuqueDaniel]

• Add pyproject.toml
• Move setup.py metadata to setup.cfg
• Add extra dependencies such as dev, docs, and test.
• Apply black formatter to setup.py
• Upgrade setup.py to Python 3 only
• Check and update classifiers
• Use a shorter description
• Bump version to 5.0.0.dev1
• Adds project_urls metadata
• Remove MANIFEST.in
• Remove Pipfile
• Update gitignore
• Remove requirements.txt