DNS Record name validation causes exception when editing records with excessively long names

[peteeckel]

Versions
NetBox Version: 3.6.4
NetBox DNS Version: 0.20.0

Describe the bug
When a record name with more than is entered in NetBox DNS, an exception is thrown instead of providing a proper error message.

To Reproduce
Steps to reproduce the behavior:

1. Edit an existing record in NetBox DNS
2. Set the name of the record to aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, with a lengh of 64 or more characters
3. Click on 'Save'

Expected result
A DNS validation error message is displayed stating that labels >63 characters are invalid, and the input is not accepted.

Actual result
An exception is raised

Screenshots