sphinx-needs 6.0 adds too many additional dependencies

```
dependencies = [
    "fqdn",
    "idna",
    "isoduration",
    "jsonpointer>1.13",
    "jsonschema==4.25.1",
    "rfc3339-validator",
    "rfc3987",
    "uri-template",
    "webcolors>=1.11",
]
```

These dependencies are being added via `jsonschema[format]` extra. It is unclear why these are required now and there is no way to opt-out.