PostgreSQL connection string for Microsoft hosted Azure pipelines agent

Per these docs, PostgreSQL server is there and service just needs to be started, no password needed. However, what is the proper connection string for Npgsql? When

Host=localhost;Database=postgres;Username=postgres

is used, an exception is thrown

Unhandled exception. Npgsql.NpgsqlException (0x80004005): No password has been provided but the backend requires one (in SASL/SCRAM-SHA-256)
   at Npgsql.NpgsqlConnector.AuthenticateSASL(List`1 mechanisms, Boolean async, CancellationToken cancellationToken)
   at Npgsql.NpgsqlConnector.Authenticate(String username, NpgsqlTimeout timeout, Boolean async, CancellationToken cancellationToken)
   at Npgsql.NpgsqlConnector.Open(NpgsqlTimeout timeout, Boolean async, CancellationToken cancellationToken)
   at Npgsql.ConnectorPool.AllocateLong(NpgsqlConnection conn, NpgsqlTimeout timeout, Boolean async, CancellationToken cancellationToken)
   at Npgsql.NpgsqlConnection.Open(Boolean async, CancellationToken cancellationToken)
   at Npgsql.NpgsqlConnection.Open()
   at PostgresqlExtensions.PostgresqlDatabase(SupportedDatabasesForEnsureDatabase supported, String connectionString, IUpgradeLog logger, X509Certificate2 certificate)
   at PostgresqlExtensions.PostgresqlDatabase(SupportedDatabasesForEnsureDatabase supported, String connectionString, IUpgradeLog logger)
   at PostgresqlExtensions.PostgresqlDatabase(SupportedDatabasesForEnsureDatabase supported, String connectionString)