create makefile, use python's native venv, use pip for install instead of setuptools

[0xalpharush]

This is outdated and likely causes/ will cause headaches for developers.

• Use python3 -m pip install -e . for editable installation instead of setuptools
• Create a makefile to do this make dev.
• Use python3 -m venv env && source ./env/bin/activate instead of requiring a tool like virtualenv https://github.com/crytic/solc-select/blob/dev/CONTRIBUTING.md#developer-environment