chore: update dockerfile

Dockerfile

@@ -7,10 +7,9 @@ RUN cargo build --release
 FROM debian:bookworm-slim
 LABEL org.opencontainers.image.authors "yinheli"
 LABEL org.opencontainers.image.source https://github.com/yinheli/kungfu
-RUN sed -i 's|deb.debian.org|mirrors.ustc.edu.cn|g' /etc/apt/sources.list && \
-    sed -i 's|security.debian.org|mirrors.ustc.edu.cn|g' /etc/apt/sources.list && \
-    apt-get update && apt-get install -y iptables
-RUN apt-get clean autoclean && apt-get autoremove --yes && rm -rf /var/lib/apt/lists/*
+RUN apt-get update && \
+    apt-get install -y iptables && \
+    apt-get clean autoclean && apt-get autoremove --yes && rm -rf /var/lib/apt/lists/*
 RUN mkdir /app
 WORKDIR /app
 COPY --from=builder /workspace/target/release/kungfu .