Drop compatibility with PHP 7.2 and 7.3

[enricobattocchi]

Tentative list:

• Remove the notification introduced in Use WHIP to deprecate PHP 7.2 and 7.3 #21014 + remove the WHIP dependency
• Remove the WHIP dependency in Premium (see https://github.com/Yoast/wordpress-seo-premium/pull/4280)
• Remove from GitHub actions linting, unit testing and integration testing for:

Tasks

Beta Give feedback

1. Free
2. Premium
3. Local SEO
4. WooCommerce SEO
5. News SEO
6. Video SEO
7. Duplicate Post
8. Test Helper
9. ACF Analysis

For reference, the previous iteration was: Drop compatibility with PHP 5.6, 7.0, 7.1

[enricobattocchi]

We should discuss with @jrfnl which patch version of 7.4.* should be set as the minimum (last time we opted for 7.2.5 because of some dependencies brought in by the scoper package)