Flexible requirements

[Pierlou]

No description provided.

[bolinocroustibat]

I don't know the project enough so maybe I miss something, but I don't know about that. For me, requirements.txt is a locked dependencies file, it needs to have the requirements pinned to have a reproducible environment.
This is especially the case here as requirements.txt is used by the CI to build the package, so it needs to be deterministic.
The pyproject.toml file can hold non-pinned dependencies, as it is a project metadata descriptor, but the lock file (requirements.txt or another one like uv.lock or poetry.lock) should always describe the project as precisely and as reproductible as possible.

[bolinocroustibat]

@Pierlou
I added in this same PR a commit as a suggestion on how to deal with project vs. pinned dependencies.
This is only an example suggestion!

Sorry I realize now that this definitely should have been a separate PR.
Feel absolutely free to revert the commit if you feel like so, or to ask me to move it to a separate PR!