Could not detect any platforms warning

my nuspec looks like

<files>
    <file src="Xpand.VersionConverter.ps1" target="build\Xpand.VersionConverter.ps1" />
    <file src="Functions.ps1" target="build\Functions.ps1" />
    <file src="..\..\src\Xpand.key\Xpand.snk" target="build\Xpand.snk" />
    <file src="Xpand.VersionConverter.targets" target="build\Xpand.VersionConverter.targets" />
    <file src="Mono.Cecil\Mono.Cecil.dll" target="build\Mono.Cecil\Mono.Cecil.dll" />
    <file src="Mono.Cecil\Mono.Cecil.Pdb.dll" target="build\Mono.Cecil\Mono.Cecil.Pdb.dll" />
    <file src="Mono.Cecil\Mono.Cecil.Rocks.dll" target="build\Mono.Cecil\Mono.Cecil.Rocks.dll" />
    <file src="Mono.Cecil\Mono.Cecil.Mdb.dll" target="build\Mono.Cecil\Mono.Cecil.Mdb.dll" />
    <file src="srcsrv\dbghelp.dll" target="build\srcsrv\dbghelp.dll" />
    <file src="srcsrv\pdbstr.exe" target="build\srcsrv\pdbstr.exe" />
    <file src="srcsrv\srcsrv.dll" target="build\srcsrv\srcsrv.dll" />
    <file src="srcsrv\srcsrv.ini" target="build\srcsrv\srcsrv.ini" />
    <file src="srcsrv\srctool.exe" target="build\srcsrv\srctool.exe" />
    <file src="ReadMe.md" target="content\Properties\Xpand.VersionConverter.ReadMe.md" />
  </files>

and when i do paket install I get this warning

Could not detect any platforms from 'Mono.Cecil' in 'C:\Users\Tolis\.nuget\packages\xpand.versionconverter\1.0.37\build\Mono.Cecil\Mono.Cecil.dll', please tell the package authors
Could not detect any platforms from 'srcsrv' in 'C:\Users\Tolis\.nuget\packages\xpand.versionconverter\1.0.37\build\srcsrv\dbghelp.dll', please tell the package authors

is there a way to avoid it?

Start with the shown .nuspec entries and reproduce the warnings using paket install. Trace how Paket handles files under build\Mono.Cecil and build\srcsrv; done means the warning is avoided or the supported way to avoid it is clearly identified.