DEV: add requirements-tests.txt on make install target

[leogrosa]

Is your feature request related to a problem? Please describe.
While trying to run ruff locally to lint and format the code, I noticed that I didn't have it installed. I thought that running make install would be enough to gather all necessary packages to develop and test the code in my computer. However, I had to run pip install -r requirements-tests.txt separately.

Describe the solution you'd like
pip install -r requirements-tests.txt should be included as a recipe in the make install target.

Additional context
No additional context.