Set user id for php fpm container

Ref #4

Hard-coded for the time being, pending a discussion about makefile
vs. other strategies for setting the id dynamically

docker-compose.yml

@@ -14,6 +14,7 @@ services:
   php:
     image: "thecoopcloud/wordpress:5.8.2-php7.4-fpm-bedrock"
     working_dir: /app
+    user: 1000:1000
     volumes:
       - ./src:/app:cached