minor #31642 FragmentListener - fix typo in annotation (henry2778)

This PR was merged into the 3.4 branch.

Discussion
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FragmentListener - fix typo in annotation

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Just a small typo I've found in fragment listener :)

Commits
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b6ff836 fix typo

src/Symfony/Component/HttpKernel/EventListener/FragmentListener.php

@@ -24,7 +24,7 @@
  * All URL paths starting with /_fragment are handled as
  * content fragments by this listener.
  *
- * If throws an AccessDeniedHttpException exception if the request
+ * Throws an AccessDeniedHttpException exception if the request
  * is not signed or if it is not an internal sub-request.
  *
  * @author Fabien Potencier <fabien@symfony.com>