Bump Microsoft.SourceLink.GitHub from 1.1.1 to 8.0.0 (#331)

Bumps [Microsoft.SourceLink.GitHub](https://github.com/dotnet/sourcelink) from 1.1.1 to 8.0.0.
- [Release notes](https://github.com/dotnet/sourcelink/releases)
- [Commits](https://github.com/dotnet/sourcelink/commits)

---
updated-dependencies:
- dependency-name: Microsoft.SourceLink.GitHub
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/Directory.Build.targets

@@ -18,7 +18,7 @@
   <ItemGroup Condition="'$(IsPackable)' == 'true'">
     <None Include="..\..\assets\icon.png" Pack="true" PackagePath="\" Visible="false" />
     <None Include="..\..\README.md" Pack="true" PackagePath="\" Visible="false" />
-    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1" PrivateAssets="All" />
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" PrivateAssets="All" />
     <PackageReference Include="MinVer" Version="4.3.0" PrivateAssets="All" />
   </ItemGroup>