Update rules for determining minimum PHP version for brand plugins

[wpscholar]

This is our current rule:

If WordPress currently recommends PHP 7.4, we support two versions prior, which would be 7.2.
See

how-we-work/5-wordpress.md

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	### PHP
	WordPress provides recommendations and minimums.
	At writing (January 2023), [WordPress recommends](https://wordpress.org/about/requirements/) PHP 7.4 and supports 5.6.20+.
	We currently support two point releases below WordPress' recommendation -- all our products must work 100% two point releases below the recommendation.
	We expect our code to execute error-free in any minimum version WordPress supports. However, we do not expect our products to be fully-functional or even functional with PHP 5.x. Reduced functionality or throwing up an upgrade screen are both acceptable if faced with writing PHP 5.x-7.1 compatible code.

We should probably create a clearer rule regarding PHP versions that take into account a few things:

• The WP recommended PHP version (see https://wordpress.org/about/requirements/ - currently 7.4; we should never be above this with our minimum)
• PHP versions compatible with WooCommerce (see https://wordpress.org/plugins/woocommerce/ - currently 7.4, treat this like the WP recommended version - probably the same anyway)
• The versions compatible with the WP versions we support (see https://make.wordpress.org/core/handbook/references/php-compatibility-and-wordpress-versions/, 7.2+ if we're looking at the minimum version that supports all of the last three versions)
• Overall WordPress PHP version stats(see https://wordpress.org/about/stats/, support anything 5% or greater)
• Internal PHP version stats (ideally based on hosting-level stats, but use Hiive as the fallback data source - Anything with more than 5% usage globally https://hiive.cloud/admin/php, or based on the brand plugin in question https://hiive.cloud/admin/brands)

If we apply all these rules without hosting-level PHP version stats, we're looking at PHP 7.2 as our lowest supported version. However, for Bluehost and HostGator we support 7.3+. That said, I think we should be fine to support PHP 7.3+ for all plugins, given the only rule that would dictate we support 7.2 would be if we support the lowest compatible version for the last 3 WP versions. If we ignore that rule the minimum becomes 7.3+ based on usage stats. Unless the hosting stats show otherwise, we'll use what we have from Hiive.