message: Replace subtle HKDF with HKDF KDF in x25519 HPKE KEM Go.
diff: @@ -96,14 +96,16 @@ func (x *x25519KEM) deriveKEMSharedSecret(dh, senderPubKey, recipientPubKey []by
  if err != nil {
  return nil, err
  }
  - info, err := labelInfo("shared_secret", ctx, suiteID, int(macLength))
  + hkdfKDF, err := newHKDFKDF(x.macAlg)
  if err != nil {
  return nil, err
  }
  - return subtle.ComputeHKDF(
  - x.macAlg,
  - labelIKM("eae_prk", dh, suiteID),
  + return hkdfKDF.extractAndExpand(
  /*salt=*/ nil,
  - info,
  - macLength)
  + dh,
  + "eae_prk",
  + ctx,
  + "shared_secret",
  + suiteID,
  + int(macLength))
  }
  