[Infra] Remove redundant version

System.Collections.Immutable is no longer used.

Author: martincostello

Directory.Packages.props

@@ -41,7 +41,6 @@
     <PackageVersion Include="Microsoft.Extensions.Options" Version="[9.0.0,)" />
     <PackageVersion Include="Microsoft.Owin" Version="[4.2.2,)" />
     <PackageVersion Include="Microsoft.Win32.Registry" Version="[5.0.0,)" />
-    <PackageVersion Include="System.Collections.Immutable" Version="[8.0.0,)" />
     <PackageVersion Include="System.Drawing.Common" Version="[4.7.2,)" />
     <PackageVersion Include="System.Net.Http" Version="[4.3.4,)" />
     <PackageVersion Include="System.Private.Uri" Version="[4.3.2,)" />