Update 1 NuGet dependencies

Author: github-actions[bot]

nanoFramework.Azure.Devices.Client.nuspec

@@ -26,7 +26,7 @@ This is an SDK for Azure IoT Hub using MQTT broker.</description>
       <dependency id="nanoFramework.Runtime.Events" version="1.10.0-preview.4" />
       <dependency id="nanoFramework.Runtime.Native" version="1.5.3-preview.4" />
       <dependency id="nanoFramework.System.Collections" version="1.3.0" />
-      <dependency id="nanoFramework.System.Net" version="1.8.0-preview.13" />
+      <dependency id="nanoFramework.System.Net" version="1.8.0-preview.15" />
       <dependency id="nanoFramework.System.Net.Http" version="1.4.0-preview.6" />
       <dependency id="nanoFramework.System.Text" version="1.1.3-preview.7" />
       <dependency id="nanoFramework.System.Threading" version="1.0.4-preview.8" />

nanoFramework.Azure.Devices.Client/Azure.Devices.Client.nfproj

@@ -85,7 +85,7 @@
       <Private>True</Private>
     </Reference>
     <Reference Include="System.Net, Version=1.8.0.0, Culture=neutral, PublicKeyToken=c07d481e9758c731">
-      <HintPath>..\packages\nanoFramework.System.Net.1.8.0-preview.13\lib\System.Net.dll</HintPath>
+      <HintPath>..\packages\nanoFramework.System.Net.1.8.0-preview.15\lib\System.Net.dll</HintPath>
       <Private>True</Private>
     </Reference>
     <Reference Include="System.Net.Http, Version=1.4.0.0, Culture=neutral, PublicKeyToken=c07d481e9758c731">

nanoFramework.Azure.Devices.Client/packages.config

@@ -6,7 +6,7 @@
   <package id="nanoFramework.Runtime.Events" version="1.10.0-preview.4" targetFramework="netnanoframework10" />
   <package id="nanoFramework.Runtime.Native" version="1.5.3-preview.4" targetFramework="netnanoframework10" />
   <package id="nanoFramework.System.Collections" version="1.3.0" targetFramework="netnanoframework10" />
-  <package id="nanoFramework.System.Net" version="1.8.0-preview.13" targetFramework="netnanoframework10" />
+  <package id="nanoFramework.System.Net" version="1.8.0-preview.15" targetFramework="netnanoframework10" />
   <package id="nanoFramework.System.Net.Http" version="1.4.0-preview.6" targetFramework="netnanoframework10" />
   <package id="nanoFramework.System.Text" version="1.1.3-preview.7" targetFramework="netnanoframework10" />
   <package id="nanoFramework.System.Threading" version="1.0.4-preview.8" targetFramework="netnanoframework10" />