build: update syncplay docker script

Dockerfile

@@ -1,13 +1,16 @@
-ARG PYTHON="python:3.9-alpine3.17"
+ARG PYTHON="python:3.9-alpine3.18"
 
-FROM ${PYTHON} as build
+FROM ${PYTHON} AS builder
 ENV SYNCPLAY="1.7.0"
 RUN apk add gcc musl-dev libffi-dev
-RUN if [ "$(getconf LONG_BIT)" == "32" ]; then apk add cargo openssl-dev; fi
+RUN sh -c '[ $(getconf LONG_BIT) -eq 64 ] || apk add cargo openssl-dev'
 RUN wget https://github.com/Syncplay/syncplay/archive/v${SYNCPLAY}.tar.gz -O- | tar xz
 WORKDIR ./syncplay-${SYNCPLAY}/
 RUN cat /dev/null > requirements_gui.txt
 RUN SNAPCRAFT_PART_BUILD=1 pip wheel --wheel-dir /wheels/ ./
+
+FROM ${PYTHON} AS syncplay
+COPY --from=builder /wheels/ /wheels/
 WORKDIR /release/local/lib/
 RUN mkdir $(basename /usr/local/lib/python3.*/) && cd ./python3.*/ && \
     ls /wheels/*.whl | xargs -P0 -n1 unzip -d ./site-packages/
@@ -15,7 +18,8 @@ COPY ./boot.py /release/bin/syncplay
 
 FROM ${PYTHON}
 RUN apk add --no-cache libffi openssl
-COPY --from=build /release/ /usr/
+COPY --from=syncplay /release/ /usr/
 ENV PYTHONUNBUFFERED=1
 EXPOSE 8999
+WORKDIR /data/
 ENTRYPOINT ["syncplay"]