Suppressed group titles should not be printed

[hamdanal]

To reproduce:

import argparse
from rich_argparse import RichHelpFormatter

parser = argparse.ArgumentParser("PROG", formatter_class=RichHelpFormatter)
group = parser.add_argument_group(title=argparse.SUPPRESS)
group.add_argument("foo")
parser.print_help()

Produces:

Usage: PROG [-h] foo

Options:
  -h, --help  show this help message and exit

==Suppress==:
  foo

Expected:

Usage: PROG [-h] foo

Options:
  -h, --help  show this help message and exit

  foo