Enable weekly tests with the JIT compiler to be added in Python 3.13

[namurphy]

Python 3.13 is expected to have a JIT compiler, though it is expected to be disabled by default and thus far only has modest performance gains. After it is released, we should add a weekly test to make sure that PlasmaPy can be run with it. We will need to wait until after a version of Numba is released for Python 3.13 as well (unless we switch to Cython).

There's a chance that the JIT compiler will encounter some issues with upstream packages (e.g., NumPy & Astropy) so we may need to raise issues in the upstream repositories. If this doesn't work right away, we can update it to the "revisit in 2026" label instead "revisit in 2025".