FIJISEPARATE corpus cannot load

### What went wrong?

The [`FIJISEPARATE` corpus class](https://github.com/CentreForDigitalHumanities/I-analyzer/blob/develop/backend/corpora/peaceportal/fiji_separate.py) raises an `AttributeError` when instantiated. The Peace Portal server includes this corpus in the settings.

### What did you expect to happen?

The class should be able to instantiate.

### Screenshot

_No response_

### Where did you find the bug?

- [ ] https://ianalyzer.hum.uu.nl
- [ ] https://peopleandparliament.hum.uu.nl
- [x] https://peace.sites.uu.nl
- [ ] a server hosted elsewhere (i.e. not by the research software lab)
- [x] a local server

### Version

5.23.0

### Steps to reproduce

On the peace portal server, run the deployment script.

In development:

Add `FIJI_ALIAS = ''` to your `settings_local.py`

Run `yarn django shell` to open the Python shell and run:

```python
from corpora.peaceportal.fiji_separate import FIJISEPARATE
FIJISEPARATE()
```