Lock down major.minor versions in requirements.txt

[n1hility]

In the run up to 0.18.0 we should lock down all of our deps to minor versions in our requirements file to prevent surprise updates coming in (e.g. like torch 2.4).

[bjhargrave]

See also #1425

[nathan-weinberg]

cc @tiran @RobotSail @leseb since they were involved in the PR linked by @bjhargrave

[n1hility]

I'm closing this in favor of using constraints per the proposal in #122

[nathan-weinberg]

@n1hility think you wanted to link instructlab/dev-docs#122