Cannot index parliament-netherlands

### What went wrong?

Indexing the People & Parliament Netherlands corpus locally failed.

Error:

```
File ".../Textcavator/backend/corpora/utils/filter_sources.py", line 10, in in_date_range
return start_date <= corpus.max_date and end_date >= corpus.min_date
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: can't compare datetime.datetime to datetime.date

```

### What did you expect to happen?

-

### Screenshot

_No response_

### Where did you find the bug?

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

### Version

5.28

### Steps to reproduce

- Add Dutch parliament corpus
- Run the index command to create an index for the corpus.