⬆️ Bump alpine from 3.21.0 to 3.21.2

Bumps alpine from 3.21.0 to 3.21.2.

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

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

Dockerfile

@@ -11,7 +11,7 @@ RUN go build -o /Jomon -ldflags "-s -w"
 
 ## run
 
-FROM alpine:3.21.0
+FROM alpine:3.21.2
 ENV TZ Asia/Tokyo
 
 RUN apk --update --no-cache add tzdata \