Use a newer debian image

Mads Jon Nielsen · Mads Jon Nielsen · commit 76183da8d55c · 2023-04-09T17:15:08.000+02:00
Former-commit-id: 625b5f3
diff --git a/Dockerfile b/Dockerfile
@@ -1,4 +1,4 @@
-FROM debian:bullseye-20210927-slim
+FROM debian:bullseye-20230320-slim
 
 RUN apt-get update && \
   apt-get install -y rsync && \
