Update dependency Microsoft.SourceLink.GitHub to v8 (#628)

+semver:patch

Author: renovate[bot]

src/Directory.Build.props

@@ -29,7 +29,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1" PrivateAssets="All"/>
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" PrivateAssets="All"/>
   </ItemGroup>
 
 </Project>