Update docker-compose.yml

Since March 2021, WordPress images use a customized wp-config.php that pulls the values directly from the environment variables. As a result of reading environment variables directly, the wpcli container also needs the same set of environment variables to properly evaluate wp-config.php

docker-compose.yml

@@ -25,6 +25,11 @@ services:
     volumes:
       - ./config/php.conf.ini:/usr/local/etc/php/conf.d/conf.ini
       - ./wp-app:/var/www/html
+    environment:
+      WORDPRESS_DB_HOST: db
+      WORDPRESS_DB_NAME: "${DB_NAME}"
+      WORDPRESS_DB_USER: root
+      WORDPRESS_DB_PASSWORD: "${DB_ROOT_PASSWORD}"
     depends_on:
       - db
       - wp