Impossible to migrate the "System.Directory.Services.Protocols" dll from version "4.0.0" to "5.0.1" with nuget (.net framework 4.8)

I have a project that uses the "System.Directory.Services.Protocols" dll which is in version 4.0 and references the framework:

C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.8\System.DirectoryServices.Protocols.dll.

I want to update the dll because there is a security hole in 5.0.0 fixed in 5.0.1.

But when I update with nuget (after removing the reference from my project), everything goes correctly (I don't get any error) but the referenced dll is still the one from framework 4.8.

I tried to reference it manually by adding it from the "net-standard 2.0" package directory

Packages\System.DirectoryServices.Protocols.5.0.1\lib    | net45\ <empty>    | net-standard2.0" Packagesystem.DirectoryServices.Protocols.5.0.1 

but it doesn't work any better.

I thought the 4.8framework was compatible with.net standard 2.0, so why doesn't it select this dll?