Update Dockerfile

Dockerfile

@@ -17,7 +17,7 @@ RUN useradd -m -s /bin/bash coder && \
 
 # 安装基础依赖和code-server
 RUN apt-get update && apt-get install -y && \
-    DEBIAN_FRONTEND=noninteractive apt-get install gcc g++ gdb clangd wget git curl jq tzdata -y && \
+    DEBIAN_FRONTEND=noninteractive apt-get install gcc g++ gdb clangd wget git curl jq tzdata cron -y && \
     curl -fsSL https://code-server.dev/install.sh | sh
 
 COPY settings.json /home/coder/.local/share/code-server/User/