Purge old images workflow failed: snok/container-retention-policy: manifest unknown

[willdavsmith]

Could be a transient issue or not, we should monitor to see

Pull down action image 'ghcr.io/snok/container-retention-policy:v3.0.1'
  /usr/bin/docker pull ghcr.io/snok/container-retention-policy:v3.0.1
  v3.0.1: Pulling from snok/container-retention-policy
  manifest unknown
  Warning: Docker pull failed with exit code 1, back off 3.803 seconds before retry.
  /usr/bin/docker pull ghcr.io/snok/container-retention-policy:v3.0.1
  v3.0.1: Pulling from snok/container-retention-policy
  manifest unknown
  Warning: Docker pull failed with exit code 1, back off 8.671 seconds before retry.
  /usr/bin/docker pull ghcr.io/snok/container-retention-policy:v3.0.1
  v3.0.1: Pulling from snok/container-retention-policy
  manifest unknown