Update Dockerfile

Author: patrikjuvonen

docker/Dockerfile

@@ -1,17 +1,17 @@
-FROM php:7.1-cli
+FROM php:7.3-cli
 
 RUN pecl install xdebug \
     && docker-php-ext-enable xdebug
 
 # Install unzip for composer dependencies
 RUN apt-get update \
     && apt-get install -y --no-install-recommends unzip \
-    && apt-get autoremove -y
+    && apt-get purge -y --autoremove
 
 ENV COMPOSER_ALLOW_SUPERUSER 1
 ENV COMPOSER_HOME /root/.composer
 
-COPY --from=composer:2.0.7 /usr/bin/composer /usr/bin/composer
+COPY --from=composer:2.0.11 /usr/bin/composer /usr/bin/composer
 
 WORKDIR /application