update Newtonsoft.Json to 13.0.3 (#168)

Author: janusw

src/GeoJSON.Net/GeoJSON.Net.csproj

@@ -17,7 +17,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
   </ItemGroup>
 
   <PropertyGroup>