请问 Laravel sail 启动后在执行 `apt-get update` 太慢了超时怎么办？

我已经把 sources.list 替换了阿里云镜像源，并且在命令行执行

apt-get update

的时候速度非常快，可见 sources.list 文件是生效了的。

但是在当我执行

./vendor/bin/sail up

的时候，由于我的 Dockerfile 中包含 apt-get update 命令，这里部署的时候也执行了更新，但是镜像并不是 sources.list 中的镜像，而是 ubuntu 的官方镜像，而且速度特别慢，没更新成功过，一直在超时。

这是我的 dockerfile

FROM ubuntu:20.04

LABEL maintainer="Taylor Otwell"

ARG WWWGROUP

WORKDIR /var/www/html

ENV DEBIAN_FRONTEND noninteractive
ENV TZ=UTC

RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone

ADD sources.list /etc/apt/

RUN apt-get update \
    && apt-get install -y gnupg gosu curl ca-certificates zip unzip git supervisor sqlite3 libcap2-bin libpng-dev python2 \
    && mkdir -p ~/.gnupg \
    && chmod 600 ~/.gnupg \
    && echo "disable-ipv6" >> ~/.gnupg/dirmngr.conf \
    && apt-key adv --homedir ~/.gnupg --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys E5267A6C \
    && apt-key adv --homedir ~/.gnupg --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys C300EE8C \
    && echo "deb https://launchpad.proxy.ustclug.org/ondrej/php/ubuntu focal main" > /etc/apt/sources.list.d/ppa_ondrej_php.list \
    && apt-get update \
    && apt-get install -y php7.4-cli php7.4-dev \
       php7.4-pgsql php7.4-sqlite3 php7.4-gd \
       php7.4-curl php7.4-memcached \
       php7.4-imap php7.4-mysql php7.4-mbstring \
       php7.4-xml php7.4-zip php7.4-bcmath php7.4-soap \
       php7.4-intl php7.4-readline php7.4-pcov \
       php7.4-msgpack php7.4-igbinary php7.4-ldap \
       php7.4-redis \
    && curl -so /usr/bin/composer https://mirrors.aliyun.com/composer/composer.phar \
    && chmod a+x /usr/bin/composer \
    && composer --version \
    && composer config -g repo.packagist composer https://mirrors.aliyun.com/composer/ \
    && curl -sL https://deb.nodesource.com/setup_15.x | bash - \
    && apt-get install -y nodejs \
    && curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - \
    && echo "deb https://dl.yarnpkg.com/debian/ stable main" > /etc/apt/sources.list.d/yarn.list \
    && apt-get update \
    && apt-get install -y yarn \
    && apt-get install -y mysql-client \
    && apt-get install -y postgresql-client \
    && apt-get -y autoremove \
    && apt-get clean \
    && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

RUN setcap "cap_net_bind_service=+ep" /usr/bin/php7.4

RUN groupadd --force -g $WWWGROUP sail
RUN useradd -ms /bin/bash --no-user-group -g $WWWGROUP -u 1337 sail

COPY start-container /usr/local/bin/start-container
COPY supervisord.conf /etc/supervisor/conf.d/supervisord.conf
COPY php.ini /etc/php/7.4/cli/conf.d/99-sail.ini
RUN chmod +x /usr/local/bin/start-container

EXPOSE 8000

ENTRYPOINT ["start-container"]

我的 sources.list 文件

deb http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse