[Bug]: Pydantic serialization error

### What happened?

A bug happened with the BFF
/{version}/ecoindexes/latest

### Project

Ecoindex API

### What OS do you use?

_No response_

### urls

_No response_

### Relevant log output

```shell
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `datetime` but got `str` - serialized value may not be as expected
ecoindex-api-backend | Expected `uuid` but got `str` - serialized value may not be as expected
ecoindex-api-backend | return self.serializer.to_python(
```

### Code of Conduct

- [X] I agree to follow this project's Code of Conduct

Reproduziere die BFF /{version}/ecoindexes/latest-Anfrage und untersuche den Pydantic-Serialisierungspfad der Route sowie die Antwortmodelle. Verfolge, warum datetime- und UUID-Werte die Serialisierung als Strings erreichen; abgeschlossen ist die Aufgabe, wenn der Endpunkt die erwartete Antwort ohne die gemeldeten Serialisierungswarnungen zurückgibt.

Vom Indexierungsmodell aus dem Issue-Text verfasst.