Certain CI runs are hanging

[Carifio24]

The CI test runs for Python >= 3.10 are hanging on Ubuntu and MacOS. After pytest finishes collecting all of the tests, it seems that something is causing it to hang up before running any of them.

I originally noticed this with #72, but the fact that this is happening with #73 (a one-line change to the manifest file) leads me to believe that this isn't an issue with our code directly, but either something with the GitHub runners or maybe with an update in an upstream dependency. Creating this issue as a place to keep track of updates on this problem.

[Carifio24]

Turns out that the culprit is a dialog that pops up due to an error with numpy 2 in the dendrogram viewer. There's a fix in glue-viz/glue-qt#19, but we can do something like xfail these tests if numpy >= 2 until that's resolved.