Get rid of the linter error:
openstack_dashboard/management/commands/migrate_settings.py:117:19: E1123:
Unexpected keyword argument 'encoding' in function call (unexpected-keyword-arg)
Change-Id: I4a8d2c7e1296541e5de03e936d97f90d6c368fd3
Signed-off-by: Radomir Dopieralski <openstack@dopieralski.pl>