Update to ligo.skymap 2.1.1

[lpsinger]

Standard information about the request

This is a: dependency update

Motivation

This version, and later versions, are compatible with both Numpy 1.x and 2.x.

Contents

Links to any issues or associated PRs

Testing performed

Additional notes

• The author of this pull request confirms they will adhere to the code of conduct

[lpsinger]

Right, this will fail now because ligo.skymap conforms to SPEC 0 so it has dropped support for Python 3.9.

[ahnitz]

@lpsinger That's something you and @titodalcanton will likely need to discuss. As far as I know, 3.9 is till required to be supported for the low latency analysis in pycbc. I'm assigning him to review.

[ahnitz]

@titodalcanton What is the plan for moving pycbc live off of 3.9? Can we drop 3.9 in pycbc (at least for testing if not officially).

[titodalcanton]

We found that moving away from 3.9 requires some changes related to MPI for PyCBC Live at CIT, and these potentially affect the latency, or at least, they lead to some behavior that we do not understand yet. So we decided to continue with 3.9 for the time being and revisit the transition to something like 3.12 once some of the current priorities start winding down. We may get to that during the upcoming commissioning break.

Also note that we also use 3.9 for the LVK virtualenvs, i.e. the current offline analyses.