Remove HTTP from dependency declaration in nuspec (#394)

Author: josesimoes

nanoFramework.Azure.Devices.Client.nuspec

@@ -23,7 +23,6 @@ This is an SDK for Azure IoT Hub using MQTT broker.</description>
       <dependency id="nanoFramework.Json" version="2.2.183" />
       <dependency id="nanoFramework.M2Mqtt" version="5.1.185" />
       <dependency id="nanoFramework.M2Mqtt.Core" version="5.1.185" />
-      <dependency id="nanoFramework.System.Net.Http" version="1.5.99" />
     </dependencies>
   </metadata>
   <files>