Modify System.Collections.Immutable reference

Updated PackageReference for System.Collections.Immutable to exclude all assets.

Author: T-Gro

tests/FSharp.Test.Utilities/FSharp.Test.Utilities.fsproj

@@ -92,8 +92,10 @@
  <NoWarn>$(NoWarn);NU1510</NoWarn> <!-- NU1510: Project is explicitly referencing the runtime assembly 'System.Collections.Immutable', however, if we remove it, it tries to find it on the wrong path. Also, local NoWarn does not help - This is just me trying to enforce it -->
 </PropertyGroup>
   <ItemGroup>
-    <!-- NU1510: Project is explicitly referencing the runtime assembly 'System.Collections.Immutable', however, if we remove it, it tries to find it on the wrong path -->
-    <PackageReference Include="System.Collections.Immutable" Version="$(SystemCollectionsImmutableVersion)" GeneratePathProperty="true" NoWarn="NU1510" />
+    <!-- NU1510: Project is explicitly referencing the runtime assembly 'System.Collections.Immutable', however, if we remove it, it tries to find it on the wrong path .
+     TEST IF WE CAN ELIMINATE THIS DIRECT REFERENCE
+    <PackageReference Include="System.Collections.Immutable" Version="$(SystemCollectionsImmutableVersion)" GeneratePathProperty="true" ExcludeAssets="all" /> --> 
+
     <PackageReference Include="Microsoft.Net.Compilers" Version="$(MicrosoftNetCompilersVersion)" />
     <PackageReference Include="Microsoft.DiaSymReader.PortablePdb" Version="$(MicrosoftDiaSymReaderPortablePdbVersion)">
       <PrivateAssets>all</PrivateAssets>