Bump library/alpine from 3.21.2 to 3.21.3

Bumps library/alpine from 3.21.2 to 3.21.3.

---
updated-dependencies:
- dependency-name: library/alpine
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Dockerfile

@@ -1,4 +1,4 @@
-FROM docker.io/library/alpine:3.21.2
+FROM docker.io/library/alpine:3.21.3
 
 LABEL org.opencontainers.image.source="https://github.com/airtower-luna/hello-ghcr" \
       org.opencontainers.image.title="Container says Meow!" \