update to 3.1.0 (#14269)

Author: poanchen

src/IotCentral/IotCentral.Test/IotCentral.Test.csproj

@@ -11,7 +11,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Azure.Management.IotCentral" Version="2.3.0" />
+    <PackageReference Include="Microsoft.Azure.Management.IotCentral" Version="3.1.0" />
   </ItemGroup>
 
 </Project>