net-mgmt/netbox: Update to 2.7.12

Changelog:

Enhancements:

• Reference VRF by name rather than RD during IP/prefix import
• Use absolute URLs in rack elevation SVG renderings
• Allow connecting cables between two circuit terminations
• Add the webhook_receiver management command to assist in troubleshooting outgoing webhooks

Bug Fixes:

• Fix typing of count_ipaddresses on interface serializer
• Fail cleanly when trying to import multiple device types simultaneously
• Fix exception when disconnecting a cable from a power feed
• Tweak display of unset custom integer fields
• Fix reservation edit/delete button URLs on rack view

https://github.com/netbox-community/netbox/releases/tag/v2.7.12

MFH: 2020Q2