Test dependencies are not latest versions from nuget

Microsoft.NET.Test.Sdk dependency and others are not the latest. Both this documentation samples and dotnet new templates are out of date. Is it possible to keep versions up to date with latest from dotnet new template or nuget?

Otherwise some mention of `dotnet list package --outdated ` run after initial setup and test might be helpful.

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#### Document Details

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* ID: 1c123f1f-8ae8-db21-2eac-4297bfc30b44
* Version Independent ID: 4675decb-333f-0508-5a3d-ce71dc85936d
* Content: [Unit testing C# with MSTest and .NET - .NET](https://docs.microsoft.com/en-us/dotnet/core/testing/unit-testing-with-mstest)
* Content Source: [docs/core/testing/unit-testing-with-mstest.md](https://github.com/dotnet/docs/blob/main/docs/core/testing/unit-testing-with-mstest.md)
* Product: **dotnet-fundamentals**
* GitHub Login: @ncarandini
* Microsoft Alias: **wiwagn**