Add php extension fileinfo only for php 7.1 and 7.2

Dockerfile

@@ -73,13 +73,13 @@ RUN echo 'hosts: files dns' > /etc/nsswitch.conf && \
     echo "http://dl-cdn.alpinelinux.org/alpine/v${ALPINE_VERSION}/community" >> /etc/apk/repositories && \
     apk update && \
     apk add --no-cache \
-        php7 php7-phar php7-json php7-dom php7-fileinfo php7-gd php7-mbstring php7-openssl \
+        php7 php7-phar php7-json php7-dom php7-gd php7-mbstring php7-openssl \
         php7-pdo php7-curl php7-xml php7-zip php7-session php7-ctype php7-iconv \
         php7-bcmath && \
     if [ "${PHP_VERSION}" = "7.0" ]; then \
       echo "no extra packages required" ; \
     else \
-      apk add --no-cache php7-tokenizer php7-simplexml php7-xmlwriter ; \
+      apk add --no-cache php7-fileinfo php7-tokenizer php7-simplexml php7-xmlwriter ; \
     fi && \
     rm /etc/apk/repositories && \
     mv /etc/apk/repositories.org /etc/apk/repositories && \