Add AnnotatedReferenceAssemblyVersion to fix build (#352)

* Add AnnotatedReferenceAssemblyVersion to fix build

* Use version 5.0.0 instead of 3.1.0

* Use version 8.0.0 instead of 3.1.0

* Add TunnelVision only for .netstandard2.0

Author: canro91

Directory.Build.props

@@ -5,9 +5,13 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
-  <ItemGroup>
+  <PropertyGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
+    <AnnotatedReferenceAssemblyVersion>5.0.0</AnnotatedReferenceAssemblyVersion>
+  </PropertyGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="TunnelVisionLabs.ReferenceAssemblyAnnotator" Version="1.0.0-alpha.160" PrivateAssets="all" />
-    <PackageDownload Include="Microsoft.NETCore.App.Ref" Version="[3.1.0]" />
+    <PackageDownload Include="Microsoft.NETCore.App.Ref" Version="[$(AnnotatedReferenceAssemblyVersion)]" />
   </ItemGroup>
 
 </Project>