Can't publish app for linux-arm64 or ubuntu-arm64

Steps to produce:

- Create a project from Windows Forms App (.Net core) template in visualstudio 2019 with .Net Core 5.0 or with .Net Core 3.1 .
- Click on build -> publish
- Change deployment mode to: Self-contained
- Change target framework to: linux-arm64 or ubuntu-arm64

Actual result: the screen display this error:

Build output is:
```
1>------ Build started: Project: test4, Configuration: Release Any CPU ------
1>You are using a preview version of .NET Core. See: https://aka.ms/dotnet-core-preview
1>test4 -> C:\Projects\test4\bin\Release\net5.0\test4.dll
2>------ Publish started: Project: test4, Configuration: Release Any CPU ------
2>Determining projects to restore...
2>Restored C:\Projects\test4\test4.csproj (in 275 ms).
2>There was no runtime pack for Microsoft.WindowsDesktop.App.WindowsForms available for the specified RuntimeIdentifier 'linux-arm64'.
========== Build: 1 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========
========== Publish: 0 succeeded, 1 failed, 0 skipped ==========

```

Expected result: Publish successfull

Is it possible to compile .Net Core WinForms app compile for ARM64 (linux-arm64 or ubuntu-arm64)?