build(deps): bump Microsoft.CodeAnalysis.CSharp from 4.7.0 to 4.8.0

Bumps [Microsoft.CodeAnalysis.CSharp](https://github.com/dotnet/roslyn) from 4.7.0 to 4.8.0.
- [Release notes](https://github.com/dotnet/roslyn/releases)
- [Changelog](https://github.com/dotnet/roslyn/blob/main/docs/Breaking%20API%20Changes.md)
- [Commits](https://github.com/dotnet/roslyn/commits)

---
updated-dependencies:
- dependency-name: Microsoft.CodeAnalysis.CSharp
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

src/Exercism.Analyzers.CSharp/Exercism.Analyzers.CSharp.csproj

@@ -7,7 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.7.0"/>
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.8.0"/>
   </ItemGroup>
 
 </Project>