Add a warning to users that they are not supported or validated by the GCM project since Mariner is non-.NET supported distro.

Author: Robin Lan

src/linux/Packaging.Linux/install-from-source.sh

@@ -198,6 +198,7 @@ case "$distribution" in
         ensure_dotnet_installed
     ;;
     mariner)
+	    print_unsupported_distro "WARNING" "$distribution"
         $sudo_cmd tdnf update -y
 
         # Install dotnet/GCM dependencies.