Version numbers from WPEngine's ACF plugin mixed into SCF plugin

[j-hoffmann]

Some @since phpdoc tags use 6.3.8 as version string. The takover form ACF happened after version 6.3.6 when it was turned into SCF. But SCF never had a version 6.3.8. This got mixed up in the messy takeover which led to code being copied from WP Engine's ACF release (in version 6.3.8) but released in SCF with different version number.

Affected code parts:
/includes/post-types/class-acf-taxonomy.php#L510
/includes/post-types/class-acf-post-type.php#L625

[kraftbj]

Thanks. I think it would make the most sense to split the old since tags off, e.g. @since ACF x.x.x vs @since SCF x.x.x too.

[priethor]

Fixed in #129