Another bug in keycloakauthenticator - check_signarure is always true

[drJabber]

Hello, team
In keycloakauthenticator readme sample there are lines, that could disable signature verification, but this lines dont work, because check_signature is always True

jupyterhub-extensions/KeyCloakAuthenticator/README.md

Lines 66 to 68 in 0997d9b

	#Configure token signature verification
	c.KeyCloakAuthenticator.check_signature=True
	c.KeyCloakAuthenticator.jwt_signing_algorithms = ["HS256", "RS256"]

I think this behavior could be fixed if in lines

jupyterhub-extensions/KeyCloakAuthenticator/keycloakauthenticator/auth.py

Lines 172 to 173 in 0997d9b

	if self.config.check_signature :
	jwks_uri = data['jwks_uri']

and

jupyterhub-extensions/KeyCloakAuthenticator/keycloakauthenticator/auth.py

Lines 194 to 195 in 0997d9b

	if not self.config.check_signature:
	options.update({"verify_signature": False})

you could change self.config.check_signature to self.check_signature

Could you please also fix this
or maybe I could make a PR?