Followup for grouping imports

This patch closes the comment [1], it groups the imports in
test_rbac_rule_validation.py

[1]https://review.opendev.org/#/c/720971/1/patrole_tempest_plugin/tests/unit/test_rbac_rule_validation.py@22

Change-Id: I916796933dc4cee84229850ad87ea6190254d548
1 file changed