How to install curl in conjunction with --no-install-recommends in Debian correctly?
you need just to install ca-certificates so update your apt-get command to :
RUN set -ex; \
    apt-get -y install --no-install-recommends \
        ca-certificates \
        curl=7.64.0-4+deb10u1 \
        unzip=6.0-23+deb10u1 \
        coreutils=8.30-3 \
        lsb-release build-essential ssh-client apt-transport-https \
        python gnupg