BAU: Bump alpine

Bumps the docker-all-dependencies group with 1 update in the /basic-auth-sidecar directory: alpine.


Updates `alpine` from 3.20 to 3.21

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

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

basic-auth-sidecar/Dockerfile.httpie

@@ -1,4 +1,4 @@
-FROM alpine:3.20
+FROM alpine:3.21
 
 RUN apk add --no-cache --update \
     httpie