[release/6.0] update the MicrosoftNetSdkWorkloadManifestReaderVersion used

[MichaelSimons]

Currently MicrosoftNetSdkWorkloadManifestReaderVersion 6.0.100-preview.5.21254.11 is used - https://github.com/dotnet/arcade/blob/release/6.0/eng/Versions.props#L86. In Preview 7 there were some breaking changes made with - dotnet/sdk@b8ade8e. Please update Arcade to build with a newer version and address the resulting build breaks:

  /repos/tarball1/src/arcade.474307e526160c813c9fd58060eb8356ccca6099/artifacts/source-build/self/src/src/Microsoft.DotNet.Build.Tasks.Workloads/src/GenerateWorkloadMsis.cs(124,33): error CS1061: 'BaseWorkloadDefinition' does not contain a definition for 'Platforms' and no accessible extension method 'Platforms' accepting a first argument of type 'BaseWorkloadDefinition' could be found (are you missing a using directive or an assembly reference?) [/repos/tarball1/src/arcade.474307e526160c813c9fd58060eb8356ccca6099/artifacts/source-build/self/src/src/Microsoft.DotNet.Build.Tasks.Workloads/src/Microsoft.DotNet.Build.Tasks.Workloads.csproj]
  /repos/tarball1/src/arcade.474307e526160c813c9fd58060eb8356ccca6099/artifacts/source-build/self/src/src/Microsoft.DotNet.Build.Tasks.Workloads/src/GenerateWorkloadMsis.cs(124,58): error CS1061: 'BaseWorkloadDefinition' does not contain a definition for 'Platforms' and no accessible extension method 'Platforms' accepting a first argument of type 'BaseWorkloadDefinition' could be found (are you missing a using directive or an assembly reference?) [/repos/tarball1/src/arcade.474307e526160c813c9fd58060eb8356ccca6099/artifacts/source-build/self/src/src/Microsoft.DotNet.Build.Tasks.Workloads/src/Microsoft.DotNet.Build.Tasks.Workloads.csproj]

This is currently impacting source-build as it requires building with the latest bits.

[riarenas]

This looks like it could be part of the new operational epic, but maybe until that's in place, and since it's impacting source-build, FR?

[markwilkie]

@ilyas1974 / @MattGal - thoughts?

[ilyas1974]

As we are still ramping up in the operations space and this is something that is needed in the short term, I am adding it to FR.

[MattGal]

Oops also needed a release/6.0 version

[MattGal]

Both PRs are merged now, and will flow with the regular dependency flow. Having moved forward to an RTM version of the package I'm optimistically closing this, @MichaelSimons please reactivate if I've missed something.