[Alpine JDK21] Bump Use Alpine to 3.18.4

[MarkEWaite]

Use Alpine 3.18.4, not 3.18.3

Passed tests in platformlabeler

jenkinsci/docker#1726 is the matching controller pull request

Testing done

None. Relying on ci.jenkins.io to perform the tests.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[gounthar]

Thanks, Mark.
As with docker-ssh-agent, I think updatecli would have updated a few days from now.
The updatecli GitHub Action has run with your PR and given this log:

#######################
# BUMP ALPINE VERSION #
#######################


SOURCES
=======

latestVersion
-------------
WARNING: ⚠ No GitHub Release found, we fallback to published git tags
Searching for version matching pattern "~3"
✔ GitHub release version "v3.18.4" found matching pattern "~3" of kind "semver"


CHANGELOG:
----------
no GitHub Release found for v3.18.4 on "https://github.com/alpinelinux/aports"


CONDITIONS:
===========

testDockerImageExists
---------------------
✔ docker image alpine:3.18.4 found

testDockerfileArg
-----------------
✔ Line "ARG ALPINE_TAG=3.18.4" found, matching the keyword "ARG" and the matcher "ALPINE_TAG".
✔ key map["keyword":"ARG" "matcher":"ALPINE_TAG"] found in Dockerfile "alpine/Dockerfile"


TARGETS
========

updateDockerBake
----------------

**Dry Run enabled**

⚠ - path "variable.ALPINE_FULL_TAG.default" updated from "3.18.3" to "3.18.4" in file "docker-bake.hcl"

updateDockerfile
----------------

**Dry Run enabled**

⚠ The line #23, matched by the keyword "ARG" and the matcher "ALPINE_TAG", is changed from "ARG ALPINE_TAG=3.18.3" to "ARG ALPINE_TAG=3.18.4".
⚠ - changed lines [23] of file "/tmp/updatecli/github/jenkinsci/docker-agent/alpine/Dockerfile"


ACTIONS
========

[Dry Run] An action of kind "github/pullrequest" is expected.

You're still faster than the bot, I can then still have faith that human beings can win against the machine... at least for a while. 🚀

[dduportal]

As expected, #513 bumped the version of Alpine Linux.

However, it did not update the jdk21 Dockerfile: as such I'm pushing a fixup commit here to ensure the updatecli manifest is updated to avoid 2 PRs in the future + I'm renaming the PR title to match its new status