boolean flag --dump-state expects argument

Currently the functionally boolean flag "--dump-state" expects an argument whereas according to the usage string, it should not. It only signals the app to dump the output into --output-dir.

miles@t440:~/repo/juju-lint$ juju-lint --dump-state -d /tmp/out -c contrib/fcb-yoga-focal.yaml -t openstack
usage: juju-lint [-h] [-l [LOGGING.LOGLEVEL]] [-d [OUTPUT.FOLDER]] [--dump-state OUTPUT.DUMP] [-c RULES.FILE] [-t CLOUD-TYPE] [-o OVERRIDE.SUBORDINATE] [--logfile LOGGING.FILE] [--format {text,json}]
                 [manual-file]
juju-lint: error: argument --dump-state: expected one argument