Bump Newtonsoft.Json in /Clients/SampleSolution.iOS

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]

Clients/SampleSolution.iOS/packages.config

@@ -1,4 +1,4 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="Newtonsoft.Json" version="12.0.3" targetFramework="xamarinios10" />
+  <package id="Newtonsoft.Json" version="13.0.2" targetFramework="xamarinios10" />
 </packages>