ipatests: webui: Use safe-loader for loading YAML configuration file

FullLoader class for YAML loader was introduced in version 5.1 which
also deprecated default loader. SafeLoader, however, stays consistent
across the versions and brings added security.

This fix is necessary as PyYAML > 5.1 is not available in downstream.

Related: https://pagure.io/freeipa/issue/9009

Signed-off-by: Michal Polovka <mpolovka@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>

ipatests/test_webui/ui_driver.py

@@ -191,7 +191,7 @@ class UI_driver:
         if not NO_YAML and os.path.isfile(path):
             try:
                 with open(path, 'r') as conf:
-                    cls.config = yaml.load(stream=conf, Loader=yaml.FullLoader)
+                    cls.config = yaml.safe_load(stream=conf)
             except yaml.YAMLError as e:
                 pytest.skip("Invalid Web UI config.\n%s" % e)
             except IOError as e: