fixup! TST: switch all jobs to Python 3.13

Author: neutrinoceros

tox.ini

@@ -7,7 +7,7 @@ envlist =
     # These are widely used packages that have historically
     # had issues with some astropy releases, so we include them here
     # as regression testing.
-    py{39,310,311,312}-{all,asdf_astropy,astropy_healpix,astroquery,ccdproc,photutils,regions,reproject,specreduce,specutils,sunpy}{,-dev}
+    py{39,310,311,312,313}-{all,asdf_astropy,astropy_healpix,astroquery,ccdproc,photutils,regions,reproject,specreduce,specutils,sunpy}{,-dev}
 
 requires =
     setuptools >= 30.3.0