Update dependency Microsoft.SourceLink.GitHub to v8

Author: renovate[bot]

Directory.Packages.props

@@ -4,7 +4,7 @@
     <CompilerGeneratedFilesOutputPath>$(BaseIntermediateOutputPath)\GeneratedFiles</CompilerGeneratedFilesOutputPath>
   </PropertyGroup>
   <ItemGroup>
-    <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="1.1.1" />
+    <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="8.0.0" />
     <PackageVersion Include="Rocket.Surgery.MSBuild.CI" Version="1.1.5" />
     <PackageVersion Include="Rocket.Surgery.MSBuild.SourceLink" Version="1.1.5" />
     <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" />