Could not detect any platforms from 'net6.0' warnings

[diegopego]

While building on Ubuntu 20.04, and windows 11, I've got these warnings.
Although the build was completed without errors, the warnings seemed serious enough for me to fill this issue.

Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.runtime.compilerservices.unsafe/6.0.0/lib/net6.0/System.Runtime.CompilerServices.Unsafe.xml', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.threading.tasks.dataflow/6.0.0/lib/net6.0/System.Threading.Tasks.Dataflow.xml', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.codedom/6.0.0/lib/net6.0/System.CodeDom.xml', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/microsoft.build/17.0.0/lib/net6.0/Microsoft.Build.xml', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.security.accesscontrol/6.0.0/lib/net6.0/System.Security.AccessControl.dll', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.text.encoding.codepages/6.0.0/lib/net6.0/System.Text.Encoding.CodePages.dll', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.security.permissions/6.0.0/lib/net6.0/System.Security.Permissions.dll', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.security.cryptography.protecteddata/6.0.0/lib/net6.0/System.Security.Cryptography.ProtectedData.dll', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.resources.extensions/6.0.0/lib/net6.0/System.Resources.Extensions.dll', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.net.http.winhttphandler/6.0.0/lib/net6.0/System.Net.Http.WinHttpHandler.xml', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.formats.asn1/6.0.0/lib/net6.0/System.Formats.Asn1.xml', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.diagnostics.diagnosticsource/6.0.0/lib/net6.0/System.Diagnostics.DiagnosticSource.xml', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.collections.immutable/6.0.0/lib/net6.0/System.Collections.Immutable.xml', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.security.cryptography.pkcs/6.0.0/lib/net6.0/System.Security.Cryptography.Pkcs.xml', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.reflection.metadata/6.0.0/lib/net6.0/System.Reflection.Metadata.dll', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.configuration.configurationmanager/6.0.0/lib/net6.0/System.Configuration.ConfigurationManager.dll', please tell the package authors
Could not detect any platforms from 'net6.0' in '/home/diego/.nuget/packages/system.security.cryptography.xml/6.0.0/lib/net6.0/System.Security.Cryptography.Xml.dll', please tell the package authors