fix: handle missing .versand_s for service categories like … (#579)

There are categories which are not require shipping and there is no
shipping field

## ℹ️ Description
For example category 297/298 does not require shipping, because its a
service category.
The current code did not handle that case and was searching for a path
with .versand_s, but in this category, there is no such path.

## 📋 Changes Summary

If the shipping_type is set to NOT_APPLICABLE in the configuration, the
shipping assignment step is skipped instead of being forced.

### ⚙️ Type of Change
Select the type(s) of change(s) included in this pull request:
- [x] 🐞 Bug fix (non-breaking change which fixes an issue)
- [ ] ✨ New feature (adds new functionality without breaking existing
usage)
- [ ] 💥 Breaking change (changes that might break existing user setups,
scripts, or configurations)


## ✅ Checklist
Before requesting a review, confirm the following:
- [x] I have reviewed my changes to ensure they meet the project's
standards.
- [x] I have tested my changes and ensured that all tests pass (`pdm run
test`).
- [x] I have formatted the code (`pdm run format`).
- [x] I have verified that linting passes (`pdm run lint`).
- [x] I have updated documentation where necessary.

By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice.

src/kleinanzeigen_bot/resources/translations.de.yaml

@@ -89,6 +89,7 @@ kleinanzeigen_bot/__init__.py:
     "Publishing ad '%s'...": "Veröffentliche Anzeige '%s'..."
     "Updating ad '%s'...": "Aktualisiere Anzeige '%s'..."
     "Failed to set shipping attribute for type '%s'!": "Fehler beim setzen des Versandattributs für den Typ '%s'!"
+    "Shipping step skipped - reason: NOT_APPLICABLE": "Versandschritt übersprungen: Versand nicht anwendbar (Status = NOT_APPLICABLE)"
     "# Payment form detected! Please proceed with payment.": "# Bestellformular gefunden! Bitte mit der Bezahlung fortfahren."
     " -> SUCCESS: ad published with ID %s": " -> ERFOLG: Anzeige mit ID %s veröffentlicht"
     " -> SUCCESS: ad updated with ID %s": " -> ERFOLG: Anzeige mit ID %s aktualisiert"