build(deps): bump Newtonsoft.Json from 13.0.1 to 13.0.3

Bumps Newtonsoft.Json from 13.0.1 to 13.0.3.

---
updated-dependencies:
- dependency-name: Newtonsoft.Json
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

CreativeCode.JWK.Tests/CreativeCode.JWK.Tests.csproj

@@ -13,6 +13,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="xunit" Version="2.9.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2"><IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>