formula_auditor: scope eol check to core tap

[apainintheneck]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew typecheck with your changes locally?
• Have you successfully run brew tests with your changes locally?

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This is not relevant information for third-party taps and requires network requests to endoflife.date so it's best to avoid them in this case.

Closes #17531

CC: @colindean

[colindean]

Thank you so much!

[Rylan12]

Makes sense to me, 👍

[MikeMcQuaid]

Thanks @apainintheneck!