Update Dockerfile

Dockerfile

@@ -7,10 +7,10 @@ RUN  \
         libfreetype6-dev \
         libjpeg62-turbo-dev \
         libmcrypt-dev \
-        libpng12-dev \
+        libpng-dev \
     && docker-php-ext-install -j$(nproc) gd mcrypt
 
 
 RUN chmod -R 777 /var/www/html/
 
-CMD ["apache2-foreground"]
+CMD ["apache2-foreground"]