updates .env-example

.env-example

@@ -2,7 +2,7 @@ DB_ROOT_PASSWORD=root
 DB_USER=user
 DB_USER_PASSWORD=user
 DOCKER_PREFIX=wp
-DOCKER_IMAGE_TAG=wp-php7.3:dev
+DOCKER_IMAGE_TAG=wp-php7.4:dev
 MOUNT_USER=username
 TRAEFIK_NETWORK_NAME=traefik
 WP_ADMIN_PASSWORD=admin
@@ -11,4 +11,4 @@ WP_DEFAULT_PROTOCOL=https
 WP_LOCALE=fr_FR
 WP_THEME=twentyseventeen
 WP_URL=www.wp.localhost
-WP_VERSION=5.4
+WP_VERSION=5.7