It turns out that "Test nightly" only builds with NumPy 2.0 but tests with NumPy 1.26.2. 🙈 In the last run of "Test nightly" it looks like matplotlib is (indirectly) forcing the downgrade to 1.26? Or maybe its a dependency of matplotlib?

Testing with NumPy 2.0 locally shows that we need to fix our code in a few places. Let's address this in two steps:

• Fix the issues with NumPy 2.0
• Make sure we can test the above fixes with NumPy 2.0 in our CI

For reference see #7249 (comment)