Bump System.Threading.RateLimiting

Bumps the dotnet group in /docs/core/extensions/snippets/ratelimit/http with 1 update: [System.Threading.RateLimiting](https://github.com/dotnet/runtime).


Updates `System.Threading.RateLimiting` from 8.0.0 to 9.0.0
- [Release notes](https://github.com/dotnet/runtime/releases)
- [Commits](dotnet/runtime@v8.0.0...v9.0.0)

---
updated-dependencies:
- dependency-name: System.Threading.RateLimiting
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: dotnet
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

docs/core/extensions/snippets/ratelimit/http/http.csproj

@@ -8,7 +8,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="System.Threading.RateLimiting" Version="8.0.0" />
+    <PackageReference Include="System.Threading.RateLimiting" Version="9.0.0" />
   </ItemGroup>
 
 </Project>