pvextractor should not be in install_requires

[pllim]

glue/setup.cfg

Line 46 in f8c1e96

pvextractor>=0.2

https://github.com/radio-astro-tools/pvextractor/blob/9911f297a7978c8afb3fe6f6d937d6b03161031c/setup.cfg#L24 (it pulls in spectral-cube)

Blocks glue-viz/glue-astronomy#76

[astrofrog]

We do rely on it for some core functionality for now. However I do have a work in progress branch to remove it as we will be doing slicing along paths In a different way.

@pllim why all the spectral-cube dislike?

[pllim]

Not particularly targeting on that package. We just want to minimize installing unused packages downstream and that was the one thing we're sure we don't need. Jdaviz is deployed on MAST and so on.