chore(deps): update alpine docker tag to v3.21.3

Author: renovate[bot]

Earthfile

@@ -13,7 +13,7 @@ COPY_METADATA:
 
 
 alpine-base:
-    FROM alpine:3.20.3@sha256:1e42bbe2508154c9126d48c2b8a75420c3544343bf86fd041fb7527e017a4b4a
+    FROM alpine:3.21.3@sha256:a8560b36e8b8210634f77d9f7f9efd7ffa463e380b75e2e74aff4511df3ef88c
     # renovate: datasource=repology depName=alpine_3_20/bash versioning=loose
     ENV BASH_VERSION="5.2.26-r0"
     RUN apk add --no-cache bash=$BASH_VERSION