Automatize GitHub Workflows and Download pipeline

[dario-coscia]

Is your feature request related to a problem? Please describe.
PINA needs to automatize and add new workflow:

1. Formatter: We can add a test to check the code is right formatted. This would remove black-formatter.yml which adds to many commits to the repo history.
2. testing_doc.yml
3. Update from setup.py to pyproject.toml since it is becoming the standard. Maybe add the possibility to download pina with conda?
4. Tests on GPUs are still missing

[ndem0]

I do not understand the issue

1. We have automatic formatting, would you like to disable it? Why?
2. ???
3. toml is already there in 0.2. For conda packaging it's better to discuss before.
4. GPUs should not be used in GH Action, how do you plan?

[dario-coscia]

1. We have automatic formatting, would you like to disable it? Why?
2. ???
3. toml is already there in 0.2. For conda packaging it's better to discuss before.
4. GPUs should not be used in GH Action, how do you plan?

1. Sorry for this, I haven't notice the change!
2. This workflow usually fails, even if the doc is built. I don't know if it is actually an issue with the workflow or the documentation.
3. Shall we open a discussion for conda?
4. Github has large runners option but they are not free.. I don't think there are alternatives (rather than local testing with a GPU)

[dario-coscia]

Conda installation moved in #503
Workflow for black formatter introduced in #401
Testing doc updated in #479