net-mgmt/netbox: Update to 3.7.3

* Remove no longer required workaround for older releases of py-markdown
  after 3bf88f00.

Changelog:

Enhancements:
* Display a human-friendly name for the OpenID Connect remote
  auth backend
* Remove associate_by_email() from default social auth pipeline
* Add PostgreSQL index for object type & ID on CachedValue table to
  improve performance
* Add "last login" time to user display & REST API serializer

Bug Fixes:
* Limit platform options by manufacturer when editing a device or
  device type
* Resolving parent location should consider assigned site when bulk
  importing locations
* Ensure changes are logged on related objects when deleting an object
  referenced via a many-to-many relationship (e.g. tags)
* Clean up formatting of link peers in bulk CSV export of cable
  termination objects
* Preserve "empty" default values for JSON custom fields
* Update existing AutoSyncRecord when changing the data file of an
  auto-synced object
* Correct IP address count link in VM interfaces table
* Fix uncaught exception when attempting invalid device bay import
* Fix inclusion of config_template field on REST API serializer for
  virtual machines
* Fix "add export template" link under "export" button on object
  list views
* Ensure protection rules are evaluated prior to enqueueing events
  when deleting an object
* Fix designation of the active tab for assigned object when modifying
  an L2VPN termination
* Correct OpenAPI schema for rack elevation REST API endpoint
* Fix unhandled exception with invalid permission constraints
* "group" field should be optional when creating VPN tunnel via
  REST API
* Add missing group column to VPN tunnels table
* Fix FHRP group representation on assignments REST API endpoint using
  brief mode
* Warn that permission constraints are not supported for reports
  or scripts
* Correct REST API schema definition for front_image & rear_image
  on DeviceType
* Ensure error messages pertaining to related objects are displayed on
  the bulk import form
* Fix exception when viewing current config when no history is present

https://github.com/netbox-community/netbox/releases/tag/v3.7.3