Text has minimum contrast [afw4f7] - Added text-shadow failing example

Hello ACT rules,

It’s me again… :D

This is a call for review to update the "Text has minimum contrast [afw4f7]" rule. The proposed change aims to add a text-shadow failing example, contrasting with the Passed Example 4, to emphasize that relying solely on text-shadow doesn't always ensure sufficient contrast.

PR: https://github.com/act-rules/act-rules.github.io/pull/2184


Call for review ends on Aug 16th.

Giacomo Petri