Add systemd ref

Signed-off-by: Clemens Vasters <clemens@vasters.com>

Author: clemensv

Directory.Packages.props

@@ -34,6 +34,7 @@
     <PackageVersion Include="Azure.Identity" Version="1.12.0" />
     <PackageVersion Include="Microsoft.Extensions.Hosting" Version="8.0.0" />
     <PackageVersion Include="Microsoft.Extensions.Hosting.WindowsServices" Version="8.0.0" />
+    <PackageVersion Include="Microsoft.Extensions.Hosting.Systemd" Version="8.0.0" />
     <PackageVersion Include="Microsoft.Extensions.Http" Version="8.0.0" />
   </ItemGroup>
 </Project>