Backport PR #16391 on branch v6.1.x (Fix endian-dependence of test introduced in gh-16380)

[meeseeksmachine]

Backport PR #16391: Fix endian-dependence of test introduced in gh-16380

[github-actions]

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• Do the proposed changes actually accomplish desired goals?
• Do the proposed changes follow the Astropy coding guidelines?
• Are tests added/updated as required? If so, do they follow the Astropy testing guidelines?
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[pllim]

Weird failures... gonna close/reopen and see.

[pllim]

aarch64 timed out but the others passed, so probably good enough for a backport PR. 🤷‍♀️

[neutrinoceros]

These timeouts have been consistent for a little while now, so I don't think it's related (but I have no idea what's causing them).