Speed field in interfaces filter is read-only

### NetBox version

v3.2.6

### Python version

3.8

### Steps to Reproduce

1. Navigate to DCIM > Interfaces and click the "Filters" tab
2. Attempt to enter an arbitrary value into the speed field

### Expected Behavior

This field should support both pre-populated and arbitrary values.

### Observed Behavior

It is not possible to enter an arbitrary value because the widget is set to read-only.