Improve autoformatting of PRs

[gomezzz]

Feature

Desired Behavior / Functionality

Ideally we want to autoformat every PR with black. Right now there is a GitHub Action in https://github.com/esa/torchquad/blob/main/.github/workflows/autoblack.yml for this. However, it doesn't work anymore and it is annoying because it adds commits to people's PRs (potentially without them noticing).

Is there a better option as a hook somewhere during merge e.g.?

What Needs to Be Done

• [ ] Replace autoblack workflow with something smarter
• [ ] Update hint regarding black in https://github.com/esa/torchquad#contributing
• [ ] Update hint regarding black in https://github.com/esa/torchquad/blob/main/docs/source/contributing.rst

How Can It Be Tested

Change should be visible on the PR for this?