reduce image size by using slim base image

CHANGELOG.md

@@ -6,6 +6,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Fixed
+- reduce image size from 276MB to 228MB by using slim base image
 - no longer assign superfluous groups `video` & `audio`
 
 ## [1.0.0] - 2019-12-22

Dockerfile

@@ -1,4 +1,4 @@
-FROM debian:buster
+FROM debian:buster-slim
 
 RUN apt-get update && apt-get install --yes --no-install-recommends \
     ca-certificates \