Ubuntu noble updates rejected: "gimagereader does not have a Release file"

[yarko]

In Ubuntu 24.04.3 LTS (noble), the ppa repository works for initial install, but then is rejected by apt update:

Reading package lists... Done
E: The repository 'https://ppa.launchpadcontent.net/sandromani/gimagereader/ubuntu noble Release' does not have a Release file.
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.