Fix benhc

Author: armallen

haskell/Dockerfile

@@ -1,8 +1,9 @@
-FROM debian:buster-slim
+FROM debian:bookwork-slim
 
 RUN \
   apt-get update && \
   apt-get install curl make ca-certificates xz-utils -y --no-install-recommends && \
+  rm -rf /var/lib/apt/lists/* && \
   curl -sSL https://get.haskellstack.org/ | sh
 
 WORKDIR /work