`i18n=Dict[LanguageTag, str]` throws warning

[PaulVanSchayck]

When using:

i18n = Dict[LanguageTag, str]

The following warning is thrown, when serializing to JSON

Expected `definition-ref` but got `LanguageTag` - serialized value may not be as expected

This seems to be related to pydantic/pydantic#6467 or pydantic/pydantic#6422.

For now, we are using:

i18n = Dict[str, str]