Fixing nuspec

Author: darkl

NuGet/WampSharp.nuspec

@@ -43,9 +43,10 @@
       </group>
       <group targetFramework="Xamarin.iOS10">
         <dependency id="Microsoft.CSharp" version="[4.3.0, )" />
-        <dependency id="System.DispatchProxy" version="[4.4.0, )" />
+        <dependency id="NETStandard.Library" version="[2.0.0, )" />
         <dependency id="System.Collections.Immutable" version="[1.3.1, )" />
         <dependency id="System.Reactive" version="[3.0.0, 3.1.1]" />
+        <dependency id="System.Reflection.DispatchProxy" version="[4.4.0, )" />
         <dependency id="System.Threading.Tasks.Dataflow" version="[4.7.0, )" />
         <dependency id="System.ValueTuple" version="[4.4.0, )" />
       </group>