minor #33690 [Security/Http] fix typo in deprecation message (nicolas-grekas)

This PR was merged into the 4.3 branch.

Discussion
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[Security/Http] fix typo in deprecation message

| Q             | A
| ------------- | ---
| Branch?       | 4.3
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

spotted by @stof in #33676

Commits
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e70057aed4 [Security/Http] fix typo in deprecation message

Author: nicolas-grekas

Firewall.php

@@ -138,7 +138,7 @@ protected function handleRequest(GetResponseEvent $event, $listeners)
             if (\is_callable($listener)) {
                 $listener($event);
             } else {
-                @trigger_error(sprintf('Calling the "%s::handle()" method from the firewall is deprecated since Symfony 4.3, implement "__invoke()" instead.', \get_class($this)), E_USER_DEPRECATED);
+                @trigger_error(sprintf('Calling the "%s::handle()" method from the firewall is deprecated since Symfony 4.3, implement "__invoke()" instead.', \get_class($listener)), E_USER_DEPRECATED);
                 $listener->handle($event);
             }