chore: Reduce the docker image size by half (#890)

docker/Dockerfile

@@ -2,13 +2,13 @@
 FROM node:16-alpine
 WORKDIR /automatisch
 
-RUN apk --no-cache add --virtual build-dependencies python3 build-base
+RUN \
+  apk --no-cache add --virtual build-dependencies python3 build-base && \
+  yarn global add @automatisch/cli@0.5.0 --network-timeout 1000000 && \
+  rm -rf /usr/local/share/.cache/ && \
+  apk del build-dependencies
 
 COPY ./entrypoint.sh /entrypoint.sh
 
-RUN yarn global add @automatisch/cli@0.5.0 --network-timeout 1000000
-
-RUN apk del build-dependencies python3 build-base
-
 EXPOSE 3000
 ENTRYPOINT ["sh", "/entrypoint.sh"]