Use Ruff formatting and linting. Install configuration moved to pyproject.toml

[keileg]

Proposed changes

This PR suggests two changes to how the PorePy project is installed and managed:

1. Information for setup/install and configuration for static checks (mypy et al) is moved from the files setup.py, setup.cfg and requirements.txt to pyproject.toml. While this is not an urgent update, it has been the recommended way of managing python projects for some years now.
2. Formatting and linting, previously handled by flake8 and black, respectively, is moved to ruff. This is primarily for the reason of speed. Note that all changes in Python files (except from setup.py) in this PR are due to this change, with formatting being the main culprit. UPDATE: Mypy forced a few additional updates, but ruff formatting is still by far the main contributor.
   Both these updates necessitated updates to the GH action files as well.

@IvarStefansson @jwboth Can you please have a look at the changes and let me know what you think? But do so after the tests have passed; I cannot I did not introduce bugs in GH action setups.

Types of changes

What types of changes does this PR introduce to PorePy?
Put an x in the boxes that apply.

• Minor change (e.g., dependency bumps, broken links).
• Bugfix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• Testing (contribution related to testing of existing or new functionality).
• Documentation (contribution related to adding, improving, or fixing documentation).
• Maintenance (e.g., improve logic and performance, remove obsolete code).
• Other: Setup, formatting, GH actions

Checklist

Put an x in the boxes that apply or explain briefly why the box is not relevant.

• The documentation is up-to-date.
• Static typing is included in the update.
• This PR does not duplicate existing functionality.
• The update is covered by the test suite (including tests added in the PR).
• If new skipped tests have been introduced in this PR, pytest was run with the --run-skipped flag.

[keileg]

@jwboth @IvarStefansson: Tests are finally passing, this should be ready for review now.

[IvarStefansson]

I like it. Am I right ruff is somewhat stricter on blank lines than black?

[keileg]

I like it. Am I right ruff is somewhat stricter on blank lines than black?

That could be, I have honestly not looked at the detailed reformatting. Life got easier when I outsourced all thinking about formatting to black, and that is a habit that is hard to break.

[jwboth]

Went through the changes, and have no objections. Ruff looks good to me.