Fix for using library as a transative dep (#71)

Author: slang25

src/EmptyFiles/EmptyFiles.csproj

@@ -9,8 +9,8 @@
     <PackageReference Include="ProjectDefaults" Version="1.0.48" PrivateAssets="All" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" Condition="$(Configuration) == 'Release'" />
     <PackageReference Include="Nullable" Version="1.3.0" PrivateAssets="All" />
-    <Content Include="buildMultiTargeting\EmptyFiles.targets" PackagePath="buildMultiTargeting\EmptyFiles.targets" />
-    <Content Include="build\EmptyFiles.targets" PackagePath="build\EmptyFiles.targets" />
+    <None Include="EmptyFiles.targets" Pack="True" PackagePath="build\EmptyFiles.targets" CopyToOutputDirectory="PreserveNewest" />
+    <None Include="EmptyFiles.targets" Pack="True" PackagePath="buildTransitive\EmptyFiles.targets" CopyToOutputDirectory="PreserveNewest" />
     <None Include="$(ProjectDir)..\..\files\**\empty.*">
       <Pack>true</Pack>
       <PackagePath>EmptyFiles</PackagePath>