[MNT]: Numpy 2.0 support strategy

Summary

Numpy will release version 2.0 around end of December 2023 with substantial API clearnup: numpy/numpy#24300

There are already some releated PRs:
#26762, #26756, #26706, #26687, #26664, #26566

This ticket should serve two purposes:

  1. Define the migration strategy
    NumPy 2.0 development status & announcements numpy/numpy#24300 (comment) has "Key guidance for users and downstream package authors"
    Are we heavy users that we have to pin <2 for now and fix everything once they have their RC out? Or could we fix everything already now (ideally still for 3.8.0)? Note that the pinning is also only a bandaid and package managers may choose to resolve to numpy=2 and matplotlib=3.7.x (which is still unpinned).
  2. Track the progress and open steps