Authentication for kibana, unknown setting xpack.security.enabled

Here is how I'm setting that with docker compose ( docker-compose.yml):

---
version: '3'
services:

  elasticsearch:
    image: docker.elastic.co/elasticsearch/elasticsearch:$ELASTIC_VERSION
    environment:
      - bootstrap.memory_lock=true
      - discovery.type=single-node
      - ELASTIC_PASSWORD=$ELASTIC_PASSWORD
      - xpack.security.enabled=$ELASTIC_SECURITY
    ulimits:
      memlock:
        soft: -1
        hard: -1
    ports:
      - 9200:9200
    networks: ['stack']

  kibana:
    image: docker.elastic.co/kibana/kibana:$ELASTIC_VERSION
    environment:
      - ELASTICSEARCH_USERNAME=elastic
      - ELASTICSEARCH_PASSWORD=$ELASTIC_PASSWORD
    ports: ['5601:5601']
    networks: ['stack']
    links: ['elasticsearch']
    depends_on: ['elasticsearch']

networks:
  stack: {}

.env file is:

ELASTIC_VERSION=7.9.3
ELASTIC_SECURITY=true
ELASTIC_PASSWORD=changeme