Bump Microsoft.SourceLink.GitHub from 1.1.1 to 8.0.0 in /src (#107)

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] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/Polyfill/Polyfill.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="ProjectDefaults" Version="1.0.101" PrivateAssets="all" />
-    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1" Condition="$(Configuration) == 'Release'" />
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" Condition="$(Configuration) == 'Release'" />
     <PackageReference Include="System.Memory" Version="4.5.5" />
     <PackageReference Include="System.ValueTuple" Version="4.5.0" />
     <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.5.4" />