Support Swift Crypto 4.x

[russellporter]

It appears there are no breaking changes in Swift Crypto 4.x that affect this project.

From Apple's notes:

Swift Crypto 4.0.0 was released in September 2025. Again the only breaking change was the addition of new cases in the CryptoError enumeration, so most users can safely depend on the 1.0.0, 2.0.0, 3.0.0, or 4.0.0 series of releases. Note that in this release _CryptoExtras was renamed to CryptoExtras. The old products and targets have been kept around for compatibility reasons, but users depending only on new code should use CryptoExtras not _CryptoExtras.

[p-x9]

Thanks!!