fix: update for mypy lint errors

Author: lepture

src/joserfc/_rfc8037/okp_key.py

@@ -94,8 +94,11 @@ class OKPKey(CurveKey[PrivateOKPKey, PublicOKPKey]):
     def exchange_derive_key(self, key: "OKPKey") -> bytes:
         # used in ECDH-ES Algorithms
         pubkey: t.Union[X25519PublicKey, X448PublicKey] = key.get_op_key("deriveKey")  # type: ignore[assignment]
-        if ((isinstance(self.private_key, X25519PrivateKey) and isinstance(pubkey, X25519PublicKey)) or
-            (isinstance(self.private_key, X448PrivateKey) and isinstance(pubkey, X448PublicKey))):
+
+        # this if else logic is used for type hints
+        if isinstance(self.private_key, X25519PrivateKey) and isinstance(pubkey, X25519PublicKey):
+            return self.private_key.exchange(pubkey)
+        elif isinstance(self.private_key, X448PrivateKey) and isinstance(pubkey, X448PublicKey):
             return self.private_key.exchange(pubkey)
         raise InvalidExchangeKeyError()