CLI arguments --fixture-graph-output-type and --fixture-graph-output-dir broken

[lukasjuhrich]

Bug

When running pytest --fixture-graph --fixture-graph-output-type=svg tests, I get the following output:

ERROR: usage: pytest [options] [file_or_dir] [file_or_dir] [...]
pytest: error: argument --fixture-graph-output-type: ignored explicit argument 'svg'

Reason

Both arguments are implemented as boolean flags due to being marked as action="store_true":

pytest-fixture-tools/pytest_fixture_tools/plugin.py

Lines 39 to 44 in 49d2ee7

	group.addoption('--fixture-graph-output-dir',
	action="store_true", dest="fixture_graph_output_dir", default="artifacts",
	help="select the location for the output of fixture graph. defaults to 'artifacts'")
	group.addoption('--fixture-graph-output-type',
	action="store_true", dest="fixture_graph_output_type", default="png",
	help="select the type of the output for the fixture graph. defaults to 'png'")

That should be omitted.
Introduced in a232b7c.