Use looser version constraints in pyproject.toml

[nbraud]

pyproject.toml currently specifies exact version constraints, like your *-requirements.txt files.

This is a problem for software distributions which package schema-salad, as then any update of any dependency breaks the build.
I encountered this when updating mypy in nixpkgs and had to patch the released version of schema-salad (applying the change from the update bot)

Many projects have a documented version policy; in the case of mypy, for instance, accepting 1.10.* (rather than 1.10.0 only) would make sense, as those would only match bugfix versions in mypy's 1.10 branch.