[HttpFoundation] Remove unused code (minor)

Remove two unused vars declaration (both are declared/computed just after)

Author: smnandre

Response.php

@@ -326,9 +326,6 @@ public function sendHeaders(?int $statusCode = null): static
 
         // headers
         foreach ($this->headers->allPreserveCaseWithoutCookies() as $name => $values) {
-            $newValues = $values;
-            $replace = false;
-
             // As recommended by RFC 8297, PHP automatically copies headers from previous 103 responses, we need to deal with that if headers changed
             $previousValues = $this->sentHeaders[$name] ?? null;
             if ($previousValues === $values) {