fix: s6

Dockerfile

@@ -8,6 +8,7 @@ LABEL description="A complete, self-hosted Tiny Tiny RSS (TTRSS) environment." \
 RUN set -xe && \
     apk update && apk upgrade && \
     apk add --no-cache --virtual=run-deps \
+    s6 s6-linux-init s6-overlay \
     busybox nginx git ca-certificates curl \
     php7 php7-fpm php7-curl php7-dom php7-gd php7-iconv php7-fileinfo php7-json \
     php7-mcrypt php7-pgsql php7-pcntl php7-pdo php7-pdo_pgsql \

root/etc/cont-init.d/50-php

@@ -3,8 +3,8 @@
 # Make sure to have a defined set of PHP binaries,
 # regardless of how the package maintainer(s) named those.
 
-rm /usr/bin/php
+rm -f /usr/bin/php
 ln -s /usr/bin/php7 /usr/bin/php
 
-rm /usr/sbin/php-fpm
+rm -f /usr/sbin/php-fpm
 ln -s /usr/sbin/php-fpm7 /usr/sbin/php-fpm