C#: Suppress NU5128 warning

[raulsntos]

Suppress dependencies of SourceGenerators package to fix NU5128.

For more context see #65532 (comment). As per the NU5128 documentation:

If your package does not contain any lib/ or ref/ files and is not a meta-package, it likely does not have any dependencies that the package consumer needs. If you are packing with NuGet's MSBuild Pack target, you can set <SuppressDependenciesWhenPacking>true</SuppressDependenciesWhenPacking> in any PropertyGroup in your project file. If you are using a custom nuspec file, remove the <dependencies> element.

This seems to be a well-known false positive in analyzer projects:

• [DCR]: Improve NU5128 warning text NuGet/Home#11354.

[akien-mga]

The rationale makes sense to me.

[YuriSizov]

Thanks!