chore: update backend lib version and update Dockerfile

backend/Dockerfile

@@ -1,5 +1,15 @@
-FROM tiangolo/uvicorn-gunicorn-fastapi:python3.9
-COPY . /app
+# 第一阶段：构建镜像
+FROM python:3.9-slim-buster AS build
+WORKDIR /app
+COPY requirements.txt .
 RUN ln -sf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime && \
     echo 'Asia/Shanghai' >/etc/timezone && \
-    pip install --no-cache-dir --upgrade -r requirements.txt -i https://pypi.tuna.tsinghua.edu.cn/simple/
+    pip install --no-cache-dir --user -r requirements.txt -i https://pypi.tuna.tsinghua.edu.cn/simple/
+COPY . .
+# 第二阶段：运行镜像
+FROM python:3.9-slim-buster
+WORKDIR /app
+COPY --from=build /root/.local /root/.local
+COPY --from=build /app .
+ENV PATH=/root/.local/bin:$PATH
+CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "80"]