Rule source on GitHub

DowngradeFlexibleHeredocSyntaxRector

Remove indentation from heredoc/nowdoc

 $query = <<<SQL
-    SELECT *
-    FROM `table`
-    WHERE `column` = true;
-    SQL;
+SELECT *
+FROM `table`
+WHERE `column` = true;
+SQL;

Configure your rector.php:

<?php

use Rector\Config\RectorConfig;
use Rector\DowngradePhp73\Rector\String_\DowngradeFlexibleHeredocSyntaxRector;

return RectorConfig::configure()
    ->withRules([
        DowngradeFlexibleHeredocSyntaxRector::class,
    ]);