Update Newtonsoft.Json dependency version (#235)

Author: dsafa

SpotifyAPI/SpotifyAPI.nuspec

@@ -15,7 +15,7 @@ For more infos, visit https://github.com/JohnnyCrazy/SpotifyAPI-NET</description
         <language />
         <tags>spotify api music .net c# spotify-client</tags>
         <dependencies>
-            <dependency id="Newtonsoft.Json" version="8.0.2" />
+            <dependency id="Newtonsoft.Json" version="10.0.3" />
         </dependencies>
     </metadata>
     <files>