EVG 9.2.8 is overly restrictive for the syntax of ISO 3166-2 states/provinces

[CBonnell]

Background: https://lists.cabforum.org/pipermail/smcwg-public/2023-April/000651.html

EVG 9.2.8 says:

3166‐2 identifier for the subdivision (state or province) of the nation in which the Registration
Scheme is operated, preceded by plus “+” (0x2B (ASCII), U+002B (UTF‐8));

This syntax is overly restrictive, as certain jurisdictions have 3 character ISO 3166-2 identifiers. We should modify the language to allow for 2 or 3 character identifiers.