Bump HotChocolate.AspNetCore from 13.7.0 to 13.8.0 in /src

Bumps [HotChocolate.AspNetCore](https://github.com/ChilliCream/graphql-platform) from 13.7.0 to 13.8.0.
- [Release notes](https://github.com/ChilliCream/graphql-platform/releases)
- [Changelog](https://github.com/ChilliCream/graphql-platform/blob/main/CHANGELOG.md)
- [Commits](ChilliCream/graphql-platform@13.7.0...13.8.0)

---
updated-dependencies:
- dependency-name: HotChocolate.AspNetCore
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

src/HotChocolateGraphQL.Backend/HotChocolateGraphQL.Backend.csproj

@@ -5,7 +5,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="HotChocolate.AspNetCore" Version="13.7.0" />
+    <PackageReference Include="HotChocolate.AspNetCore" Version="13.8.0" />
   </ItemGroup>
 
   <ItemGroup>