Remove unnecessary dependencies

Dockerfile

@@ -1,26 +1,20 @@
+FROM debian:buster-slim AS setup
+
+COPY setup.sh /bin/
+RUN bash /bin/setup.sh
+
+
 FROM debian:buster-slim
 LABEL maintainer="Xiaonan Shen <s@sxn.dev>"
 
 EXPOSE 25/tcp
 EXPOSE 143/tcp
-ENV DEB_URL https://protonmail.com/download/protonmail-bridge_1.2.6-1_amd64.deb
-WORKDIR /root
 
 # Copy gpg parameters and .deb installer
-COPY gpgparams /protonmail/
+COPY gpgparams install.sh entrypoint.sh /protonmail/
+COPY --from=setup /protonmail/protonmail.deb /protonmail/
 
 # Install dependencies and protonmail bridge
-RUN apt-get update \
-    && apt-get install -y --no-install-recommends socat pass \
-    && apt-get install -y wget \
-    && wget -O /protonmail/protonmail.deb ${DEB_URL} \
-    && apt-get install -y --no-install-recommends /protonmail/protonmail.deb \
-    && apt-get purge -y wget \
-    && apt-get autoremove -y \
-    && rm -rf /var/lib/apt/lists/* \
-    && rm /protonmail/protonmail.deb
+RUN bash /protonmail/install.sh
 
-COPY entrypoint.sh /bin/
-RUN chmod +x /bin/entrypoint.sh
-
-ENTRYPOINT ["/bin/entrypoint.sh"]
+ENTRYPOINT ["bash", "/protonmail/entrypoint.sh"]