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] <[email protected]>

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.20.3
+FROM alpine:3.21.0
 
 # Define args for the target platform so we can identify the binary in the Docker context.
 # These args are populated by Docker. The values should match Go's GOOS and GOARCH values for