Increase scikit-image minimum required version?

[tcompa]

As of recently-released v0.22:

Change number of returned arguments in skimage.registration.phase_cross_correlation. The function now always returns the 3 arguments shift, error, and phasediff (#7166). https://scikit-image.org/docs/stable/release_notes/release_0.22.html

In our code we call this function as

        shifts = phase_cross_correlation(
            np.squeeze(img_ref), np.squeeze(img_cycle_x)
        )[0]

It's not yet clear to me what to expect if we use versions <0.22, and whether we need to strictly require >=0.22.

[tcompa]

It turns out that this feature is there since at least v0.17.0 (see https://github.com/scikit-image/scikit-image/blob/v0.17.2/skimage/registration/_phase_cross_correlation.py#L266-L268), which is already older than our currently required version (we require >=0.19).

Closing.