Update version of FSharp.SystemTextJson to 1.1.23

[moinessim]

Use net6.0 since net5.0 is not supported

Use fluid version of JsonConverterOptions

Allow SkippableOptionFields, since the lack of it was causing tests to fail

[moinessim]

Hi @panesofglass,

Thank you very much for your work in this library!

I would like to contribute with this update, because I have a dependency conflict with other libraries that reference new versions of FSharp.SystemTextJson that lack a certain method.

Dotnet resolves the new version and breaks the execution of FSharp.Data.JsonSchema.

Please let me know if there are any other changes needed to merge this.

Regards

[Eliemer]

@panesofglass Merging this and potentially also working on a net 8 version would be greatly appreciated. I can contribute to the latter one

[moinessim]

@panesofglass Merging this and potentially also working on a net 8 version would be greatly appreciated. I can contribute to the latter one

Hi @Eliemer, I published a pre-release version for net8.0 from my fork. You may give it a try!

[panesofglass]

@moinessim I've been away from F# for awhile, so I apologize for not responding. I saw all your work on your fork, and I've requested you be made a maintainer of the fsprojects fork. I hope that works out, and thank you for continuing to support this project!