chore(deps): bump alpine from 3.20.3 to 3.21.0

Bumps alpine from 3.20.3 to 3.21.0.

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

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

Dockerfile

@@ -20,7 +20,7 @@ RUN go install
 
 ################################################################################
 
-FROM alpine:3.20.3 AS runtime
+FROM alpine:3.21.0 AS runtime
 COPY --from=builder /go/bin/textimg /usr/local/bin/
 COPY --from=builder /tmp/MyricaM.TTC /usr/share/fonts/truetype/myrica/MyricaM.TTC
 COPY --from=builder /usr/local/src/noto-emoji/png/128 /usr/share/emoji-image