Wrong target version for value types mapped to multiple columns

The [note about multi column vale type mapping](https://docs.microsoft.com/en-us/ef/core/modeling/value-conversions?tabs=data-annotations#composite-value-objects) still mentions EFCore 6.0 as target, while it is on the 7.0 milestone currently as stated in https://github.com/dotnet/efcore/issues/13947#issuecomment-1113299012

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* ID: 03dfe9f6-e831-ac3f-0b90-acb9b4c0f828
* Version Independent ID: a26156d1-a4b3-7df0-e63e-b8e9f804abbf
* Content: [Value Conversions - EF Core](https://docs.microsoft.com/en-us/ef/core/modeling/value-conversions?tabs=data-annotations#examples)
* Content Source: [entity-framework/core/modeling/value-conversions.md](https://github.com/dotnet/EntityFramework.Docs/blob/main/entity-framework/core/modeling/value-conversions.md)
* Product: **entity-framework**
* Technology: **entity-framework-core**
* GitHub Login: @ajcvickers
* Microsoft Alias: **avickers**