Bootstrap collapse class overrides Django class

## Details
- OS (Operating System) version: Debian Bullseye
- Browser and browser version: Chrome 100
- Django version: 3.2
- Martor version & theme: 1.6.13

### Steps to reproduce

1. Define inline class
class ObjectInline(GenericTabularInline):
model = Object
classes = ("collapse",)

2. Bootstrap rule overrides Django css and Inline becomes not colapsed but invisible.
```
.collapse:not(.show) {
display: none;
}
```