VARBYTE is decoded into utf-8

In readme VARBYTE is stated as supported as Python's `bytes` type. When trying to query data VARBYTE data from Redshift, 'utf-8' decoding error is thrown.

### Reproduction

```python
import redshift_connector

DROP_DDL = "drop table if exists varbyte_repro"
CREATE_DDL = """create table varbyte_repro(
my_var varbyte
);
"""
INSERT_DML = "insert into varbyte_repro(my_var) values (from_hex(SHA1('hello')))"
QUERY = "select * from varbyte_repro"

with redshift_connector.connect(
host="replaced",
database="replaced",
user="replaced",
password="replaced",
) as conn, conn.cursor() as cursor:
conn.autocommit = True
cursor.execute(DROP_DDL)
cursor.execute(CREATE_DDL)
cursor.execute(INSERT_DML)
cursor.execute(QUERY)
```

### Expected

Last `cursor.execute` runs without issue (so that later something like `cursor.fetchall` could be used)

### Actual

Error thrown:
```
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xaa in position 0: invalid start byte
```

Ejecute la reproducción de Python proporcionada contra Redshift e inspeccione la ruta de decodificación de resultados VARBYTE del conector cuando se ejecuta la consulta final. Confirme que los valores VARBYTE se devuelven como bytes de Python sin un UnicodeDecodeError y, después, añada o actualice la cobertura para el comportamiento de consulta demostrado.

Escrito por el modelo de indexación a partir del texto del issue.