Bump Newtonsoft.Json from 6.0.4 to 13.0.1 in /Demos/WebForms/src

Bumps [Newtonsoft.Json](https://github.com/JamesNK/Newtonsoft.Json) from 6.0.4 to 13.0.1.
- [Release notes](https://github.com/JamesNK/Newtonsoft.Json/releases)
- [Commits](JamesNK/Newtonsoft.Json@6.0.4...13.0.1)

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

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

Author: dependabot[bot]

Demos/WebForms/src/packages.config

@@ -19,7 +19,7 @@
   <package id="Microsoft.Net.Compilers" version="1.0.0" targetFramework="net45" developmentDependency="true" />
   <package id="Microsoft.Web.Infrastructure" version="1.0.0.0" targetFramework="net45" />
   <package id="Modernizr" version="2.6.2" targetFramework="net45" />
-  <package id="Newtonsoft.Json" version="6.0.4" targetFramework="net45" />
+  <package id="Newtonsoft.Json" version="13.0.1" targetFramework="net45" />
   <package id="Node-Kit" version="11.1.0.1" targetFramework="net45" />
   <package id="Respond" version="1.2.0" targetFramework="net45" />
   <package id="WebGrease" version="1.5.2" targetFramework="net45" />