Bump MQTT library (#15)

Author: Ellerbach

Azure.Devices.DeviceClient/Azure.Devices.DeviceClient.nfproj

@@ -64,8 +64,9 @@
       <Private>True</Private>
     </Reference>
     <Reference Include="nanoFramework.M2Mqtt, Version=5.0.2.0, Culture=neutral, PublicKeyToken=c07d481e9758c731">
-      <HintPath>..\packages\nanoFramework.M2Mqtt.5.0.2-preview.12\lib\nanoFramework.M2Mqtt.dll</HintPath>
+      <HintPath>..\packages\nanoFramework.M2Mqtt.5.0.2-preview.15\lib\nanoFramework.M2Mqtt.dll</HintPath>
       <Private>True</Private>
+      <SpecificVersion>True</SpecificVersion>
     </Reference>
     <Reference Include="nanoFramework.Runtime.Events, Version=1.9.2.0, Culture=neutral, PublicKeyToken=c07d481e9758c731">
       <HintPath>..\packages\nanoFramework.Runtime.Events.1.9.2-preview.5\lib\nanoFramework.Runtime.Events.dll</HintPath>

Azure.Devices.DeviceClient/packages.config

@@ -2,7 +2,7 @@
 <packages>
   <package id="nanoFramework.CoreLibrary" version="1.10.5" targetFramework="netnanoframework10" />
   <package id="nanoFramework.Json" version="2.1.0" targetFramework="netnanoframework10" />
-  <package id="nanoFramework.M2Mqtt" version="5.0.2-preview.12" targetFramework="netnanoframework10" />
+  <package id="nanoFramework.M2Mqtt" version="5.0.2-preview.15" targetFramework="netnanoframework10" />
   <package id="nanoFramework.Runtime.Events" version="1.9.2-preview.5" targetFramework="netnanoframework10" />
   <package id="nanoFramework.Runtime.Native" version="1.5.1" targetFramework="netnanoframework10" />
   <package id="nanoFramework.System.Collections" version="1.2.0" targetFramework="netnanoframework10" />