chore(deps): Bump busybox from 0fc05e4 to b4771ab in /mu-plugins

Bumps busybox from `0fc05e4` to `b4771ab`.

---
updated-dependencies:
- dependency-name: busybox
  dependency-type: direct:production
...

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

mu-plugins/Dockerfile

@@ -12,7 +12,7 @@ RUN rsync -a -r --delete --exclude-from="/mu-plugins-ext/.dockerignore" --exclud
 RUN mkdir /shared
 
 FROM ghcr.io/automattic/vip-container-images/helpers:v1@sha256:9f77c3da2ca0394d5846a9fc4195041f59ff5821ea6a7aaa43a08f15d28bf1eb AS helpers
-FROM busybox:stable-musl@sha256:0fc05e424940109068f4d6562b699da2563cd8521a35d7b216a5b0c51fb29281
+FROM busybox:stable-musl@sha256:b4771ab006a5344931341972e1e4b1ff14db2c327eeab0053416aa2277213b1d
 
 COPY --from=build --link /shared /shared
 COPY --from=helpers /rsync /usr/bin/rsync