Remove the Makefile in the root folder

[hugsy]

Description/Motivation/Screenshots

tests can be fully controlled through pytest only
linting can be fully controlled through pylint only

so there's no reason to keep the makefile in the root folder

also add pytest-cov for pytest

Against which architecture was this tested ?

"Tested" indicates that the PR works and the unit test (i.e. make test) run passes without issue.

• x86-32
• x86-64
• ARM
• AARCH64
• MIPS
• POWERPC
• SPARC
• RISC-V

Checklist

• My PR was done against the dev branch, not main.
• My code follows the code style of this project.
• My change includes a change to the documentation, if required.
• If my change adds new code, adequate tests have been added.
• I have read and agree to the CONTRIBUTING document.