v6.2.8

Fixes

• enforce a single recipient when decrypting dir and ECDH-ES (505c383)
• reject a non-string "alg" in EmbeddedJWK (714f870)

Refactor

• index the JWS and JWE registries without a wrapper (925f3bb)
• name the "alg" source in unsupported algorithm failures (1500459)