Development Roadmap and Future of ModOpt.

[paquiteau]

I reckon that I have started multiple PRs, moving forward here is a proposition for the integration of this work.

I would recommend we use a squash+rebase strategie, to minimize the effect on the main trunk. To smooth things up here is what I propose:

• [x] 1. merge the CI-update (#268) into develop
• [x] 1.5 fix the test due to astropy upgrade (#272)
• [x] 2. pull develop and merge the test refactorisation PR (#266) ~~(- [ ] 3. pull develop and merge the PnP PR (#265))~~
• [x] 3. merge the Example2Test PR (#277)
• [ ] 4. pull develop and merge the ADMM PR (#263)
• [ ] 5. Run Black once, and update the test to use --black check. There should also be modification of isort ^1

In a later future (e.g. start of Q2 2023), taking the opportunity of a coding sprint: 7. Write test for the new algorithms. This might also be the opportunity to revisite the significance of all optimisation algorithm, to solve a less dummy problem (for instance a LASSO regularised least square) 8. Move the configuration to pyproject.toml , and maybe use a src layout ^2, -> this seems to be the new standard ^3 9. Release a new ModOpt version (2.0 ? ) 10. Write new a paper about it, add it to zenodo^5 to get a DOI for the package.