activate bleeding edge phpstan rules (#2898)

src/Command/InstallCommand.php

@@ -35,19 +35,14 @@ final class InstallCommand extends Command
     public const ERROR_DATABASE = 8;
     public const ERROR_MIGRATIONS = 32;
 
-    /**
-     * @var string
-     */
-    private $rootDir;
     /**
      * @var Connection
      */
     private $connection;
 
-    public function __construct(string $projectDirectory, Connection $connection)
+    public function __construct(Connection $connection)
     {
         parent::__construct();
-        $this->rootDir = $projectDirectory;
         $this->connection = $connection;
     }