Feature request: disable date parsing

[fenollp]

In getkin/kin-openapi#698 we've found the need to tune how dates/datetimes are serialized.

This issue is asking for a setting to disable special de/serialization of dates such as 1344-08-22. A package wide setting would be fine.

Thanks

[fenollp]

For example around lines 300 of this large file: https://github.com/APIs-guru/openapi-directory/blob/f7207cf0a5c56081d275ebae4cf615249323385d/APIs/unicourt.com/1.0.0/openapi.yaml you'll find map keys that this yaml package unmarshals as time.Date (instead of just string).

 376 │                     days:
 377 │                       2023-01-25: 817
 378 │                       2023-01-26: 817
 379 │                       2023-01-27: 817
 380 │                       2023-01-28: 0
 381 │                       2023-01-29: 0

[fenollp]

Fixed in oasdiff/yaml3#8 & oasdiff#9