Bump alpine

Bumps alpine from 3.16.8 to 3.16.9.

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

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

src/test/resources/org/jvnet/hudson/plugins/platformlabeler/alpine/3.16.8/Dockerfile

@@ -1 +1 @@
-FROM alpine:3.16.8
+FROM alpine:3.16.9