Sphinx installation error

I follow the steps according to official parrot website to install sphinx, during sudo apt update, I receive the following:

Err:6 https://debian.parrot.com noble InRelease
403 Forbidden [IP: 2600:9000:2045:dc00:1a:1dfb:a480:93a1 443]
Reading package lists… Done

E: The repository ‘https://debian.parrot.com noble InRelease’ is not signed.
N: Updating from such a repository can’t be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

Sphinx is not yet compatible with Noble Numbat. The list of compatible Linux distributions is here: System requirements - 2.15.1