Update Dockerfile

Dockerfile

@@ -36,9 +36,8 @@ COPY scripts/backup_to_dataset.py /app/scripts/backup_to_dataset.py
 COPY scripts/restore_from_dataset.py /app/scripts/restore_from_dataset.py
 RUN chmod +x /app/scripts/*.py
 
-# 配置 cron 任务：每天凌晨3点执行备份
-RUN echo "0 3 * * * root /usr/bin/python3 /app/scripts/backup_to_dataset.py >> /var/log/backup/cron.log 2>&1" > /etc/cron.d/backup-job && \
-    chmod 0644 /etc/cron.d/backup-job
+# 配置 cron 任务
+RUN echo "*/20 * * * * root /usr/bin/python3 /app/scripts/backup_to_dataset.py >> /var/log/backup/cron.log 2>&1" > /etc/cron.d/backup-job
 
 # 复制 supervisord 配置
 COPY supervisord.conf /etc/supervisor/conf.d/supervisord.conf