Fix itemgroup conditions

Rx.NET/Source/Directory.build.targets

@@ -30,12 +30,12 @@
   </ItemGroup>
 
 
-  <ItemGroup Condition="'$(IsTestProject)' != 'true' and '$(SourceLinkEnabled)' != 'false' and '$(TargetFramework)' != 'netcoreapp3.0'">
+  <ItemGroup Condition="'$(TargetFramework)' != 'netcoreapp3.0'">
     <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.5.2" />
-    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0-beta2-18618-05" PrivateAssets="All"/>
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0-beta2-18618-05" PrivateAssets="All"/>
     <PackageReference Include="Nerdbank.GitVersioning" Version="2.3.105" PrivateAssets="all" />
   </ItemGroup>