[python] Fix postponed model imports

[OliverTetzTT]

The postponed model imports are wrong when the mapping name is not equal to the model name.

See Issue for example schema and further description.

I changed the method used in the python pydantic generators to use the model name for the postponed imports instead of the mapping name of the discriminator mapping.

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[fa0311]

Looks Good To Me

[OliverTetzTT]

Is there any reason, why this is not merged? Is something missing? :)

[wing328]

@OliverTetzTT sorry for the delay as there are too many PRs.

Will merge once all tests pass

[OliverTetzTT]

@wing328 no problem. I was just wondering. I might have some other contributions coming and wanted to make sure I made things right 😄

[wing328]

Just merged. Look forward to your PRs. Have a good day.