Doctrine.yaml“不包含有效的YAML:不能在无引号的映射值中使用冒号

doctrine:
    dbal:
        connections:
            default:
                url: mysql://user:password@localhost:3306/dbname

doctrine:
    dbal:
        connections:
            default:
                url: "mysql://user:password@localhost:3306/dbname"

doctrine:
    dbal:
        connections:
            default:
                driver: 'pdo_mysql'
                server_version: '5.7'
                charset: utf8mb4
                url: "mysql://user:password@localhost:3306/dbname"
    orm:
        auto_generate_proxy_classes: true
        naming_strategy: doctrine.orm.naming_strategy.underscore
        auto_mapping: true
        mappings:
            App:
                is_bundle: false
                type: annotation
                dir: '%kernel.project_dir%/src/Entity'
                prefix: 'App\Entity'
                alias: App