Don't install libzip for more recent php versions

Author: matthiasmullie

Dockerfile

@@ -5,8 +5,8 @@ COPY . /var/www
 WORKDIR /var/www
 
 RUN apt-get update
-RUN apt-get install -y zip unzip zlib1g-dev
-RUN docker-php-ext-install zip
+RUN then apt-get install -y zip unzip zlib1g-dev
+RUN if [[ `php-config --vernum` -ge 73000 ]]; then docker-php-ext-install zip; fi
 RUN docker-php-ext-install pcntl
 RUN curl -sS https://getcomposer.org/installer | php
 RUN mv composer.phar /usr/local/bin/composer