chore(deps): bump alpine from 3.20 to 3.21

Bumps alpine from 3.20 to 3.21.

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

Signed-off-by: dependabot[bot] <[email protected]>

Dockerfile.musl

@@ -42,7 +42,7 @@ RUN cargo build \
     --target x86_64-unknown-linux-musl \
     --profile deploy
 
-FROM alpine:3.20
+FROM alpine:3.21
 
 ARG STORAGE=/storage
 ARG TARGET_DIR=/iroha/target/x86_64-unknown-linux-musl/deploy