Bump Newtonsoft.Json from 10.0.3 to 13.0.1 in /sandbox/Sandbox

Bumps [Newtonsoft.Json](https://github.com/JamesNK/Newtonsoft.Json) from 10.0.3 to 13.0.1.
- [Release notes](https://github.com/JamesNK/Newtonsoft.Json/releases)
- [Commits](JamesNK/Newtonsoft.Json@10.0.3...13.0.1)

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

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

Author: dependabot[bot]

sandbox/Sandbox/Sandbox.csproj

@@ -9,7 +9,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.NETCore.Portable.Compatibility" Version="1.0.1" />
     <PackageReference Include="MsgPack.Cli" Version="0.7.1" />
-    <PackageReference Include="Newtonsoft.Json" Version="10.0.3" />
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
     <PackageReference Include="protobuf-net" Version="2.1.0" />
     <PackageReference Include="ZeroFormatter" Version="1.6.4" />
   </ItemGroup>