Bump Newtonsoft.Json version (#338)

Co-authored-by: Eugene Che <[email protected]>

Author: eugeneyche

dropbox-sdk-dotnet/Dropbox.Api/Dropbox.Api.csproj

@@ -14,7 +14,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.2" />
   </ItemGroup>
 
   <ItemGroup>