FIX: `delete_many` not working properly in sync Django backend 🚑️

OPT: Update all non-major dependencies ⬆️

OPT: add Python 3.13

OPT: remove Python 3.8 support

OPT: Bump idna from 3.6 to 3.7

Bumps [idna](https://github.com/kjd/idna) from 3.6 to 3.7.
- [Release notes](https://github.com/kjd/idna/releases)
- [Changelog](https://github.com/kjd/idna/blob/master/HISTORY.rst)
- [Commits](kjd/idna@v3.6...v3.7)

---
updated-dependencies:
- dependency-name: idna
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

OPT: Update all non-major dependencies ⬆️

OPT: Update dependency django to v5 ⬆️

OPT: Update all non-major dependencies ⬆️

OPT: updated code to Pydantic 2.0 (get rid of deprecation warnings) (#98

)

- use Pydantic 2.x syntax

---------

Co-authored-by: wieri494 <peter.wieringa@kpn.com>
Co-authored-by: Pavel Perestoronin <pavel.perestoronin@kpn.com>

OPT: improve typing for `_CachedCallable` 🧑‍💻