Remove redundant 'Update' PackageReference from Statiq.Sass.csproj.

Author: jasonsummers

src/extensions/Statiq.Sass/Statiq.Sass.csproj

@@ -5,7 +5,6 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="SharpScss" Version="3.0.0" />
-    <PackageReference Update="Microsoft.SourceLink.GitHub" Version="8.0.0" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\core\Statiq.Common\Statiq.Common.csproj" />