Use instanceof to check if the operation

Using getOperationType isn't a good idea as it would break with composer 1. This method would work for both composer 1 and 2.

src/Patches.php

@@ -176,7 +176,7 @@ public function gatherPatches(PackageEvent $event) {
     $operations = $event->getOperations();
     $this->io->write('<info>Gathering patches for dependencies. This might take a minute.</info>');
     foreach ($operations as $operation) {
-      if ($operation->getOperationType() == 'install' || $operation->getOperationType() == 'update') {
+      if ($operation instanceof InstallOperation || $operation instanceof UpdateOperation) {
         $package = $this->getPackageFromOperation($operation);
         $extra = $package->getExtra();
         if (isset($extra['patches'])) {