Avoid System.Net.Http compile error when targeting net472

Directory.Build.targets

@@ -4,5 +4,10 @@
     <EmbedUntrackedSources Condition=" '$(UseWPF)' == 'true' ">false</EmbedUntrackedSources>
   </PropertyGroup>
 
+  <ItemGroup>
+    <!-- Avoid compile error about missing namespace when combining ImplicitUsings with .NET Framework target frameworks. -->
+    <Using Remove="System.Net.Http" Condition="'$(TargetFrameworkIdentifier)'=='.NETFramework'" />
+  </ItemGroup>
+
   <Import Project="$(_WpfTempProjectNuGetFilePathNoExt).targets" Condition="'$(_WpfTempProjectNuGetFilePathNoExt)' != '' and Exists('$(_WpfTempProjectNuGetFilePathNoExt).targets')"/>
 </Project>