CI fixes

This MR should fix many of the currently failing tests:

• remove the use of scipy functionality removed in v1.14 (scipy.intergrate.simps, scipy.interpolate.interp2d)
• a change in how previously added live points are removed in dynesty to prepare for the deprecation announced here

This won't fix the healpy issues, for that we'll either need to pin the version of scipy in the CI or wait for a new release of healpy.