Fix Microsoft.ML.DataView references (#5136)

The assembly in the package references Collections.Immutable, but the nuget package doesn't. This can cause errors if someone just references the Microsoft.ML.DataView package.

Fixing by adding the reference.

Author: eerhardt

pkg/Microsoft.ML.DataView/Microsoft.ML.DataView.nupkgproj

@@ -6,6 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="System.Collections.Immutable" Version="$(SystemCollectionsImmutableVersion)" />
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
   </ItemGroup>