chore(container): update public.ecr.aws/docker/library/alpine docker tag to v3.21.3 (#32043)

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 | patch | `3.21.2` -> `3.21.3` |
|
[public.ecr.aws/docker/library/alpine](https://hub.docker.com/_/alpine)
([source](https://redirect.github.com/alpinelinux/docker-alpine)) |
final | patch | `3.21.2` -> `3.21.3` |

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containers/apps/nextcloud-imaginary/Dockerfile

@@ -11,7 +11,7 @@ RUN set -ex; \
         vips-poppler; \
     go install github.com/h2non/imaginary@b632dae8cc321452c3f85bcae79c580b1ae1ed84
 
-FROM public.ecr.aws/docker/library/alpine:3.21.2@sha256:56fa17d2a7e7f168a043a2712e63aed1f8543aeafdcee47c58dcffe38ed51099
+FROM public.ecr.aws/docker/library/alpine:3.21.3@sha256:a8560b36e8b8210634f77d9f7f9efd7ffa463e380b75e2e74aff4511df3ef88c
 
 # hadolint ignore=DL3018
 RUN set -ex; \

containers/apps/nextcloud-push-notify/Dockerfile

@@ -1,4 +1,4 @@
-FROM public.ecr.aws/docker/library/alpine:3.21.2@sha256:56fa17d2a7e7f168a043a2712e63aed1f8543aeafdcee47c58dcffe38ed51099
+FROM public.ecr.aws/docker/library/alpine:3.21.3@sha256:a8560b36e8b8210634f77d9f7f9efd7ffa463e380b75e2e74aff4511df3ef88c
 
 SHELL ["/bin/ash", "-eo", "pipefail", "-c"]
 # hadolint ignore=DL3018

containers/apps/traefik/Dockerfile

@@ -1,7 +1,7 @@
 FROM public.ecr.aws/docker/library/traefik:v3.3.3@sha256:f1fdee7fda041872cff24e36a08f45ca53f006ded88f743a8e30e3d87ca52b48
 # Above line used by CI to find tags etc
 
-FROM public.ecr.aws/docker/library/alpine:3.21.2@sha256:56fa17d2a7e7f168a043a2712e63aed1f8543aeafdcee47c58dcffe38ed51099 as plugins
+FROM public.ecr.aws/docker/library/alpine:3.21.3@sha256:a8560b36e8b8210634f77d9f7f9efd7ffa463e380b75e2e74aff4511df3ef88c as plugins
 
 # FIXME: Find a way to keep versions up to date
 # -- Use the following prefixes to specify plugins to clone