The version of System.Text.Json is too old

The version is too old
https://github.com/segmentio/Serialization.NET/blob/main/Serialization.NET/Serialization.NET.csproj

```
<PackageReference Include="System.Text.Json" Version="7.0.3" />
```

Could we upgrade to the latest due to it's vulnerability?
https://github.com/advisories/GHSA-hh2w-p6rv-4g7w