Try testing against AstroPy 6 RC.

tox.ini

@@ -72,6 +72,9 @@ commands =
     which pip
     which pytest
     pip install git+https://github.com/GeminiDRSoftware/AstroFaker#egg=AstroFaker
+    pip install --no-deps astropy-iers-data
+    conda remove --force -y astropy
+    pip install --no-deps --ignore-installed --no-input astropy==6.0.0rc2
     conda list
     noop: python -c "pass"  # just install deps & ensure python runs
     unit: python -m coverage run --rcfile={toxinidir}/.coveragerc -m pytest -v --dragons-remote-data --durations=20 -m "not integration_test and not gmosls and not f2 and not f2ls and not f2image and not gsaoi and not gsaoiimage and not niri and not nirils and not niriimage and not gnirs and not gnirsls and not gnirsimage and not wavecal and not regression and not slow" {posargs:astrodata geminidr gemini_instruments gempy recipe_system}