Use the correct digest method for placeholder

app/models/concerns/foreman_passwordstate/host_managed_extensions.rb

@@ -126,7 +126,7 @@ module ForemanPasswordstate
       host_pass(root_user, password_hash: operatingsystem&.password_hash)
     rescue StandardError => e
       logger.error "Failed to get root_pass for #{self} - #{e.class}: #{e}"
-      return Digest::SHA256.digest("#{id}-PlaceholderDueToPasswordstateError")
+      return Digest::SHA256.hexdigest("#{id}-PlaceholderDueToPasswordstateError")
     end
 
     def remove_passwordstate_passwords!