bug #30749 [Serializer] Added check of constuctor modifiers to AbstractNormalizer (NekaKawaii)

This PR was submitted for the 4.2 branch but it was merged into the 3.4 branch instead (closes #30749).

Discussion
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[Serializer] Added check of constuctor modifiers to AbstractNormalizer

| Q             | A
| ------------- | ---
| Branch?       |  4.2
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #30748
| License       | MIT

If constructor is not public, instantiate target object without constructor to prevent errors like `Access to non-public constructor of class Target`

Commits
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eb0e14c298 [Serializer] Added check of constuctor modifiers to AbstractNormalizer

src/Symfony/Component/Serializer/Normalizer/AbstractNormalizer.php

@@ -333,6 +333,10 @@ abstract class AbstractNormalizer extends SerializerAwareNormalizer implements N
 
         $constructor = $this->getConstructor($data, $class, $context, $reflectionClass, $allowedAttributes);
         if ($constructor) {
+            if (true !== $constructor->isPublic()) {
+                return $reflectionClass->newInstanceWithoutConstructor();
+            }
+
             $constructorParameters = $constructor->getParameters();
 
             $params = [];