minor symfony#59483 [OptionsResolver] Add missing support of union type in changelog (alamirault)

This PR was merged into the 7.3 branch.

Discussion
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[OptionsResolver] Add missing support of union type in changelog

| Q             | A
| ------------- | ---
| Branch?       | 7.3
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Issues        | Fix #... <!-- prefix each issue number with "Fix #", no need to create an issue if none exists, explain below instead -->
| License       | MIT

I found changelog is missing while documenting symfony/symfony-docs#20531

Code PR: symfony#59354

Commits
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946278f [OptionsResolver] Add missing support of union type

Author: fabpot

src/Symfony/Component/OptionsResolver/CHANGELOG.md

@@ -1,10 +1,15 @@
 CHANGELOG
 =========
 
+7.3
+---
+
+ * Support union type in `OptionResolver::setAllowedTypes()` method
+
 6.4
 ---
 
-* Improve message with full path on invalid type in nested option
+ * Improve message with full path on invalid type in nested option
 
 6.3
 ---