[RC] Bump to 1.6.2

* Roll back on roundcube/roundcubemail image since roundcubeorg/roundcubemail disappeared...
* Remove step which disappeared from https://github.com/roundcube/roundcubemail-docker#building-a-docker-image

roundcube/Dockerfile

@@ -1,4 +1,4 @@
-FROM roundcubeorg/roundcubemail:latest-apache
+FROM roundcube/roundcubemail:1.6.2-apache
 
 RUN a2enmod remoteip; \
     echo "RemoteIPHeader X-Forwarded-For" > /etc/apache2/conf-available/remoteip.conf; \
@@ -24,13 +24,7 @@ RUN set -ex; \
         --apcu-autoloader \
         require \
             roundcube/carddav \
-    ; \
-    composer \
-        --working-dir=/usr/src/roundcubemail/ \
-        --prefer-dist --no-dev \
-        --no-interaction \
-        --optimize-autoloader --apcu-autoloader \
-        update;
+    ;
 
 RUN mkdir -p /etc/enigma/gnupg \
  && chown www-data:www-data /etc/enigma/gnupg \