Inconsistent styling of custom fields in filter & bulk edit forms

[jeremystretch]

NetBox version

v3.1.5

Python version

3.7

Steps to Reproduce

1. Add a custom field for sites (or any model)
2. View the sites list and click the "filters" tab

Expected Behavior

The custom field should appear at the bottom of the filters form with the same styling as the other fields.

Observed Behavior

The custom field appears, but is not styled consistently.

[ryanmerolle]

wow nice catch... that's a subtle detail I would likely have never caught.

[jeremystretch]

I can't take credit for this actually; Danko Trajkovic on the NetDev Slack spotted it. I believe it was due to some recent refactoring of the base form classes.