Fail to install CF CLI on Ubuntu 24.04 due to "The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 172B5989FCD21EF8"

Please fill out the issue checklist below and provide ALL the requested information.

• I reviewed open and closed github issues that may be related to my problem.
• I tried updating to the latest version of the CF CLI to see if it fixed my problem.
• I attempted to run the command with CF_TRACE=1 to help debug the issue. --> not applicable
• I am reporting a bug that others will be able to reproduce.

Describe the bug and the command you saw an issue with

https://github.com/cloudfoundry/cli/wiki/V8-CLI-Installation-Guide#windows states under "Debian and Ubuntu" that

(apt update && apt install --yes curl gnupg) > /dev/null 2>&1

# Add the Cloud Foundry GPG key
curl -fsSL https://packages.cloudfoundry.org/debian/cli.cloudfoundry.org.key | gpg --dearmor -o /usr/share/keyrings/cloudfoundry-keyring.gpg

# Add the Cloud Foundry repository
echo "deb [signed-by=/usr/share/keyrings/cloudfoundry-keyring.gpg] https://packages.cloudfoundry.org/debian stable main" | tee /etc/apt/sources.list.d/cloudfoundry.list

apt update > /dev/null 2>&1

shall be executed.

What happened
The command apt update fails on Ubuntu 24.04 with the error message

Get:4 https://cf-cli-debian-repo.s3.amazonaws.com stable InRelease [4,368 B]
Err:4 https://cf-cli-debian-repo.s3.amazonaws.com stable InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 172B5989FCD21EF8
Reading package lists... Done
W: GPG error: https://cf-cli-debian-repo.s3.amazonaws.com stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 172B5989FCD21EF8
E: The repository 'https://packages.cloudfoundry.org/debian stable 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.

Expected behavior
The installation is possible based on the descriptions provided.

Exact Steps To Reproduce
See above.

Provide more context
Performed 2025-01-24 with fresh installation of Ubuntu 24.04

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 24.04.1 LTS
Release:        24.04
Codename:       noble

Suggested solution
It appears that simply

chmod 0644  /usr/share/keyrings/cloudfoundry-keyring.gpg

is missing in between.
As the file only contains the public key, it appears not to be security issue, relaxing the file modes.
Further details can also be found at https://stackoverflow.com/a/71384057.

Start with the Debian and Ubuntu section of the V8 CLI Installation Guide linked in the issue and reproduce the commands on Ubuntu 24.04. Check the keyring command and the suggested file-mode step; done means the documented installation completes without the NO_PUBKEY error.