chore(container): update public.ecr.aws/docker/library/alpine:3.21.3 docker digest to (#35088)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
|
[public.ecr.aws/docker/library/alpine](https://hub.docker.com/_/alpine)
([source](https://redirect.github.com/alpinelinux/docker-alpine)) |
stage | digest | `a8560b3` -> |
|
[public.ecr.aws/docker/library/alpine](https://hub.docker.com/_/alpine)
([source](https://redirect.github.com/alpinelinux/docker-alpine)) |
final | digest | `a8560b3` -> |

---

> [!WARNING]
> Some dependencies could not be looked up. Check the Dependency
Dashboard for more information.

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined),
Automerge - At any time (no schedule defined).

🚦 **Automerge**: Enabled.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the
rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about these
updates again.

---

- [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check
this box

---

This PR has been generated by [Renovate
Bot](https://redirect.github.com/renovatebot/renovate).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzOS4yMzguMCIsInVwZGF0ZWRJblZlciI6IjM5LjIzOC4wIiwidGFyZ2V0QnJhbmNoIjoibWFzdGVyIiwibGFiZWxzIjpbImF1dG9tZXJnZSIsInJlbm92YXRlL2NvbnRhaW5lciIsInR5cGUvZGlnZXN0Il19-->

containers/apps/traefik/Dockerfile

@@ -1,7 +1,7 @@
 FROM public.ecr.aws/docker/library/traefik:3.3.6@sha256:83f3c843133530e4aa45e6ddc415488583a8a01c88adc5022d415c6e97ceeaae
 # Above line used by CI to find tags etc
 
-FROM public.ecr.aws/docker/library/alpine:3.21.3@sha256:a8560b36e8b8210634f77d9f7f9efd7ffa463e380b75e2e74aff4511df3ef88c as plugins
+FROM public.ecr.aws/docker/library/alpine:3.21.3 as plugins
 
 # FIXME: Find a way to keep versions up to date
 # -- Use the following prefixes to specify plugins to clone