Bump DRF to 3.9.1 to address WS-2019-0037
Bump DRF to 3.9.1 to address WS-2019-0037

lampwins/netbox,digitalocean/netbox,digitalocean/netbox,lampwins/netbox,lampwins/netbox,lampwins/netbox,digitalocean/netbox,digitalocean/netbox