Bump debian

Bumps debian from unstable-20240408-slim to unstable-20240423-slim.

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

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

src/test/resources/org/jvnet/hudson/plugins/platformlabeler/debian/unstable/Dockerfile

@@ -1,2 +1,2 @@
-FROM debian:unstable-20240408-slim
+FROM debian:unstable-20240423-slim
 RUN apt-get update && apt-get dist-upgrade -y && apt-get install -y lsb-release