EXP: try patched jplephem (address numpy-dev deprecations) - #19184

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the change doesn't seem to be taken into account. I'm actually not sure uv pip install takes uv.sources into account, or maybe that's another problem with how tox-uv integrates with uv. I'll need to inquire a bit more.

I confirmed that uv pip install does respect [tool.uv.sources] locally.

ah but there's a catch: tox builds the project (astropy) as a sdist and installs that, so [uv.tool.sources] is effectively lost before it gets a chance to be read.
Too bad. I'll need to hack around tox.ini to achieve this instead...

Interestingly, this experiment revealed that fixing jplephem only brings out a new, previously undetected, failure mode in the same set of coordinates tests. Let's try to fix this here. I'll open a separate PR with only the relevant pieces if successful.

perfect. The only 2 tests still failing here are being addressed in #19182. I'll now move the one important change from here to a dedicated PR