Remove the vendor directory in .gitignore as these dependencies are needed for php-imap

plugins/php-imap/vendor/phar-io/manifest/src/exceptions/InvalidApplicationNameException.php

@@ -0,0 +1,17 @@
+<?php declare(strict_types = 1);
+/*
+ * This file is part of PharIo\Manifest.
+ *
+ * Copyright (c) Arne Blankerts <arne@blankerts.de>, Sebastian Heuer <sebastian@phpeople.de>, Sebastian Bergmann <sebastian@phpunit.de> and contributors
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ */
+namespace PharIo\Manifest;
+
+use InvalidArgumentException;
+
+class InvalidApplicationNameException extends InvalidArgumentException implements Exception {
+    public const InvalidFormat = 2;
+}