bug #653 [Turbo] Fix checking "topics" option in Broadcaster (wooky)

This PR was merged into the 2.x branch.

Discussion
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[Turbo] Fix checking "topics" option in Broadcaster

Mercure Broadcaster class was checking for the "topic" option, which is incorrect. This fixes that by checking for "topics" option instead.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Tickets       | Fix #... <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT

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Commits
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17129ec [Turbo] Fix checking "topics" option in Broadcaster

src/Turbo/src/Bridge/Mercure/Broadcaster.php

@@ -70,7 +70,7 @@ public function broadcast(object $entity, string $action, array $options): void
             throw new \InvalidArgumentException(sprintf('Cannot broadcast entity of class "%s" as option "rendered_action" is missing.', $entityClass));
         }
 
-        if (!isset($options['topic']) && !isset($options['id'])) {
+        if (!isset($options['topics']) && !isset($options['id'])) {
             throw new \InvalidArgumentException(sprintf('Cannot broadcast entity of class "%s": either option "topics" or "id" is missing, or the PropertyAccess component is not installed. Try running "composer require property-access".', $entityClass));
         }