TST: adapt a test to pytest<8 - #17143

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Thanks! Should have run Extra CI though to be sure.

Kicked off a run here on main: https://github.com/astropy/astropy/actions/runs/11257102100

I'll bug you if the exotic archs don't pass. 😉

I'll bug you if the exotic archs don't pass.

please do !

They passed. Thanks again!