Bump default traefik version installed (currently 2.10.7)

[consideRatio]

https://github.com/traefik/traefik/releases

traefik-proxy/jupyterhub_traefik_proxy/install.py

Lines 147 to 160 in 8940966

	parser.add_argument(
	"--traefik-version",
	dest="traefik_version",
	# default version to install should be regularly updated, see
	# https://github.com/traefik/traefik/releases
	default="2.10.7",
	help=textwrap.dedent(
	"""\
	The version of traefik to download.
	If no version is provided, it defaults to:
	--- %(default)s ---
	"""
	),
	)

[minrk]

closed by #258