minor #21801 [2.8] Fix issues reported by static analyse (romainneutron)

This PR was merged into the 2.8 branch.

Discussion
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[2.8] Fix issues reported by static analyse

| Q             | A
| ------------- | ---
| Branch?       | 2.8
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT

Followup #21800

Commits
-------

cb14bfd [2.8] Fix issues reported by static analyse

src/Symfony/Bundle/FrameworkBundle/CacheWarmer/TemplateFinder.php

@@ -14,6 +14,7 @@ namespace Symfony\Bundle\FrameworkBundle\CacheWarmer;
 use Symfony\Component\HttpKernel\KernelInterface;
 use Symfony\Component\Finder\Finder;
 use Symfony\Component\Templating\TemplateNameParserInterface;
+use Symfony\Component\Templating\TemplateReferenceInterface;
 use Symfony\Component\HttpKernel\Bundle\BundleInterface;
 
 /**

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

@@ -11,6 +11,7 @@
 
 namespace Symfony\Component\HttpKernel\EventListener;
 
+use Symfony\Component\HttpFoundation\Session\SessionInterface;
 use Symfony\Component\HttpKernel\Event\GetResponseEvent;
 use Symfony\Component\HttpKernel\KernelEvents;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;

src/Symfony/Component/Templating/PhpEngine.php

@@ -455,7 +455,7 @@ class PhpEngine implements EngineInterface, \ArrayAccess
                         $value = iconv($that->getCharset(), 'UTF-8', $value);
                     }
 
-                    $callback = function ($matches) use ($that) {
+                    $callback = function ($matches) {
                         $char = $matches[0];
 
                         // \xHH