Bump Newtonsoft.Json in /Backends/SampleSolution.Backend

Bumps [Newtonsoft.Json](https://github.com/JamesNK/Newtonsoft.Json) from 12.0.3 to 13.0.2.
- [Release notes](https://github.com/JamesNK/Newtonsoft.Json/releases)
- [Commits](JamesNK/Newtonsoft.Json@12.0.3...13.0.2)

---
updated-dependencies:
- dependency-name: Newtonsoft.Json
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Backends/SampleSolution.Backend/SampleSolution.Backend.csproj

@@ -21,7 +21,7 @@
     <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="5.0.1" />
     <PackageReference Include="Microsoft.Extensions.Hosting" Version="5.0.0" />
     <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="5.0.1" />
-    <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.2" />
     <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="5.0.1" />
     <PackageReference Include="Swashbuckle.AspNetCore" Version="5.6.3" />
   </ItemGroup>