additional container slimming

Dockerfile

@@ -6,7 +6,8 @@ ENV DEBIAN_FRONTEND noninteractive
 
 RUN apt-get update && \
     apt-get -y install python3 virtualenv mpv paxctl && \
-    apt-get clean all
+    apt-get clean && \
+    rm -rf -- /var/lib/apt/lists
 
 # Workaround: pulseaudio client library likes to remove /dev/shm/pulse-shm-*
 #             files created by the host, causing sound to stop working.