Fix merge

Author: nicolas-grekas

src/Flex.php

@@ -22,6 +22,8 @@
 use Composer\EventDispatcher\EventSubscriberInterface;
 use Composer\Factory;
 use Composer\Installer;
+use Composer\Installer\InstallerEvent;
+use Composer\Installer\InstallerEvents;
 use Composer\Installer\PackageEvent;
 use Composer\Installer\PackageEvents;
 use Composer\Installer\SuggestedPackagesReporter;