Bump Newtonsoft.Json in /src/ImmutableDotNet.Serialization.Newtonsoft
Bumps [Newtonsoft.Json](https://github.com/JamesNK/Newtonsoft.Json) from 6.0.1 to 13.0.1.
- [Release notes](https://github.com/JamesNK/Newtonsoft.Json/releases)
- [Commits](https://github.com/JamesNK/Newtonsoft.Json/compare/6.0.1...13.0.1)
---
updated-dependencies:
- dependency-name: Newtonsoft.Json
dependency-type: direct:production
...
Signed-off-by: dependabot[bot] <support@github.com>