docker: Add volume support

.github/workflows/Dockerfile.ci.alpine

@@ -66,9 +66,12 @@ RUN echo http://mirror.math.princeton.edu/pub/alpinelinux/edge/testing/ >> /etc/
     --ingroup "$USER" \
     --no-create-home \
     --uid "$UID" \
-    "$USER"
+    "$USER" && \
+    mkdir -p /data && \
+    chown $USER:$USER /data
 COPY --from=lldap --chown=$CONTAINERUSER:$CONTAINERUSER /lldap /app
 COPY --from=lldap --chown=$CONTAINERUSER:$CONTAINERUSER /docker-entrypoint.sh /docker-entrypoint.sh
+VOLUME ["/data"]
 WORKDIR /app
 ENTRYPOINT ["tini", "--", "/docker-entrypoint.sh"]
 CMD ["run", "--config-file", "/data/lldap_config.toml"]