feat(alpine): Pin Alpine version to 3.18.0

[gounthar]

In the hope of using dependabot to keep Alpine up to date, I'm proposing to fix first of all the Alpine version we use, as well as the Java 11 and 17 versions we use for Alpine.
I've already done the same for ssh-agent.

Testing done

docker buildx bake alpine_jdk11 --load

and

docker buildx bake alpine_jdk17 --load

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

[timja]

is dependabot able to update this?

[gounthar]

I do hope so.

[dduportal]

I'm interested if you find a solution for doing this with Dependabot?
As per dependabot/feedback#154, it does not seem it is possible.

I understand the goal here would be to use updatecli as it's already working on the agent images?
Btw, I've opened updatecli/updatecli#1378

[gounthar]

That is the final goal for this PR, yes. 🤷
Thanks.

[timja]

Renovate should be able to do this as well without needing to add update cli:
https://docs.renovatebot.com/modules/manager/regex/

somewhat similar:
renovatebot/renovate#16439 (comment)

[dduportal]

👍