PINT default ephemeris location is broken

[dlakaplan]

https://data.nanograv.org/static/data/ephem/ is the top ephemeris mirror in pint.solar_system_ephemerides, but I get a 403 error when I try to access it. It may not be an issue if the astropy cache works instead but it seems like we should update those locations if they are no longer correct.

[dlakaplan]

@JPGlaser : any idea?

[dlakaplan]

Hi, @JPGlaser or @nategarver-daniels . Not urgent, but just pinging on this in case you have any ideas.

[paulray]

Yeah, this still give 403 error for me.
I thought the original issue was that we were hitting the JPL servers too much during CI testing.
If that isn't needed, we should just remove this mirror site and use the main JPL repo.
The astropy caching should keep us from hitting the servers too often.