minor #12787 [Security] Remove unused use statement (cmen)

This PR was merged into the 4.3 branch.

Discussion
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[Security] Remove unused use statement

**NonceExpiredException** has been removed in Symfony 4.

Commits
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0dfdb64 Remove unused use statement

Author: javiereguiluz

security/custom_authentication_provider.rst

@@ -203,7 +203,6 @@ the ``PasswordDigest`` header value matches with the user's password::
     use Symfony\Component\Security\Core\Authentication\Provider\AuthenticationProviderInterface;
     use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;
     use Symfony\Component\Security\Core\Exception\AuthenticationException;
-    use Symfony\Component\Security\Core\Exception\NonceExpiredException;
     use Symfony\Component\Security\Core\User\UserProviderInterface;
 
     class WsseProvider implements AuthenticationProviderInterface