Update changelogs from fern repo (#5609)

Co-authored-by: dsinghvi <10870189+dsinghvi@users.noreply.github.com>

Author: fern-support

fern/products/sdks/generators/php/changelog/2026-05-22.mdx

@@ -1,3 +1,12 @@
+## 2.10.4
+**`(fix):`** Generated discriminated unions no longer emit a `fromJson()` override. The base
+`JsonSerializableType::fromJson` now uses late static binding (`static::jsonDeserialize`)
+so subclasses' typed `jsonDeserialize` overrides dispatch correctly. This eliminates ~50
+lines of duplicated code per union and resolves a PHPStan strict failure where the union
+override's `$decodedJson` was narrowed to `array<array-key, mixed>` instead of
+`array<string, mixed>`.
+
+
 ## 2.10.3
 **`(chore):`** Bump Node.js base image from 24.15 to 24.16.