Add separate migration so that all systems have the same schema after hotfix

lib/Migration/Version0007Date202211111100.php

@@ -0,0 +1,23 @@
+<?php
+declare(strict_types=1);
+
+namespace OCA\GPodderSync\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\Migration\IOutput;
+
+class Version0007Date202211111100 extends \OCP\Migration\SimpleMigrationStep {
+        public function changeSchema(IOutput $output, Closure $schemaClosure, array $options) {
+                /** @var ISchemaWrapper $schema */
+                $schema = $schemaClosure();
+
+                $table = $schema->getTable('gpodder_subscriptions');
+                $table->dropIndex('subscriptions_url_user');
+                $table->addUniqueIndex(['url', "user_id"], 'subscriptions_url_user', [ 
+                        'lengths' => [ 500, 200 ]
+                ]);
+
+                return $schema;
+        }
+}