Merge #2308

2308: Update alpine-linux to 3.14.5 - Zlib security FIX (backport #2302) r=mergify[bot] a=mergify[bot]

This is an automatic backport of pull request #2302 done by [Mergify](https://mergify.com).
Cherry-pick of a54a7841 has failed:
```
On branch mergify/bp/1.9/pr-2302
Your branch is up to date with 'origin/1.9'.

You are currently cherry-picking commit a54a7841.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   core/admin/Dockerfile
	both modified:   core/dovecot/Dockerfile
	both modified:   core/nginx/Dockerfile
	both modified:   core/none/Dockerfile
	both modified:   core/postfix/Dockerfile
	both modified:   optional/clamav/Dockerfile
	both modified:   optional/fetchmail/Dockerfile
	both modified:   optional/radicale/Dockerfile
	both modified:   optional/unbound/Dockerfile
	both modified:   setup/Dockerfile

no changes added to commit (use "git add" and/or "git commit -a")
```


To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

---


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Co-authored-by: Will <will@packer-output-c8fcfb40-3d93-4475-8f87-e14a9dd683b6>
Co-authored-by: Florent Daigniere <nextgens@users.noreply.github.com>