Recognise Ed25519 in X509_certificate_type

Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3585)

crypto/x509/x509type.c

@@ -41,6 +41,9 @@ int X509_certificate_type(const X509 *x, const EVP_PKEY *pkey)
     case EVP_PKEY_EC:
         ret = EVP_PK_EC | EVP_PKT_SIGN | EVP_PKT_EXCH;
         break;
+    case NID_ED25519:
+        ret = EVP_PKT_SIGN;
+        break;
     case EVP_PKEY_DH:
         ret = EVP_PK_DH | EVP_PKT_EXCH;
         break;