[swift6] Add typed throws to Validation functions

[x-sheep]

Swift 6 allows for the throws keyword to specify the type of error being thrown. In the case of Validation, this will save one unboxing/casting operation and make the result easier to use.

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[wing328]

https://app.bitrise.io/build/50334c36-d425-407b-85ff-43f35bf4f9fc

can you please review the build failure when you've time?

[x-sheep]

The alamofireLibrary project is already broken on the master branch, I think?

[4brunu]

The alamofireLibrary is locked into an old version prior to Alomofire migrating to Swift 6, which work with the openapi generator Swift 6 client, so it should not affect the pipelines.

[4brunu]

I closed and reopened this PR to try to trigger the pipelines again.

[4brunu]

CI is still failing, but I think this is not related to this PR. I will investigate a bit more.

[4brunu]

I have built this project locally and it works.
The issue seams to be related to server where the tests are executed.
I'm going to merge this PR, as the CI failure are not related to it.