astropy v5.3rc1 ready for testing

[Simon Conseil]

Hi everyone,

The first release candidate (RC) of the core astropy package for the
v5.3 release is now available and ready for testing!

If you are interested in trying it out, you can install this release
candidate by doing:

pip install astropy --pre

or

pip install astropy==5.3rc1

You can find the documentation corresponding to this release at:

https://docs.astropy.org/en/v5.3rc1/

including the full list of changes for this release:

https://docs.astropy.org/en/v5.3rc1/changelog.html

as well as a 'What's new in v5.3?' page:

https://docs.astropy.org/en/v5.3rc1/whatsnew/5.3.html

We would appreciate if you could try out this RC and report back any
success or failure via the following wiki page:

https://github.com/astropy/astropy/wiki/v5.3-RC-testing

For example, you can try running the test suite as mentioned on the
wiki page. In addition, if you maintain any packages that use astropy,
please check that your package(s) works well with this RC and let us
know if there are any issues or whether everything works fine. There
is a section to list packages that work/don't work at the bottom of
the wiki page. Please also open an issue in the astropy core package
issue
tracker for any issues you encounter (and open separate issues for
each problem you run into).

If you use conda, be sure to either remove the existing conda astropy
package or make a new environment before installing the RC. Note that
there are no conda packages for the RC.

Thanks!
Simon (release manager for v5.3)