add --skip-checks to runserver_plus

[tasiotas]

Please add --skip-checks to runserver_plus.

Django has it since 3.0
https://docs.djangoproject.com/en/4.2/ref/django-admin/#runserver

Thank you

[varunsaral]

django-extensions/django_extensions/management/commands/runserver_plus.py

Lines 390 to 395 in dd794f1

	try:
	check_errors(self.check)(display_num_errors=self.show_startup_messages)
	check_errors(self.check_migrations)()
	handler = check_errors(self.get_handler)(**options)
	except Exception as exc:
	self.stderr.write("Error occurred during checks: %r" % exc, ending="\n\n")

I think we can move this to if block after adding --skip-checks in handler