add dos2unix prestage

docker/Dockerfile

@@ -1,11 +1,16 @@
 # syntax=docker/dockerfile:1
+
+FROM alpine
+
+COPY ./entrypoint.sh /entrypoint.sh
+
+RUN apk add --no-cache dos2unix && \
+    dos2unix /entrypoint.sh
+
 FROM node:16-alpine
 WORKDIR /automatisch
 
-RUN apt-get update && apt-get install -y dos2unix
-
-COPY ./entrypoint.sh /entrypoint.sh
-RUN dos2unix /entrypoint.sh && apt-get --purge remove -y dos2unix && rm -rf /var/lib/apt/lists/*
+COPY --from=0 /entrypoint.sh /entrypoint.sh
 
 RUN yarn global add @automatisch/cli@0.2.0