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 regression and not slow" {posargs:astrodata geminidr gemini_instruments gempy recipe_system}