Update changelogs from fern repo (#4315)

Co-authored-by: jsklan <100491078+jsklan@users.noreply.github.com>

Author: fern-support

fern/products/sdks/overview/typescript/changelog/2026-03-16.mdx

@@ -1,3 +1,10 @@
+## 3.57.2
+**`(fix):`** Fix map types with unknown/any value types to not include spurious `| undefined`.
+Previously, `map<string, UnknownType>` generated `Record<string, UnknownType | undefined>`
+instead of `Record<string, UnknownType>`. The `| undefined` is now correctly omitted
+from map value types.
+
+
 ## 3.57.1
 **`(fix):`** Fix passthrough `fetch()` method producing 404s when the SDK environment is an
 object (e.g. `{ base: string; production: string }`) instead of a plain string URL.