Update changelogs from fern repo (#4435)

Co-authored-by: iamnamananand996 <31537362+iamnamananand996@users.noreply.github.com>

Author: fern-support

fern/products/sdks/overview/rust/changelog/2026-03-20.mdx

@@ -0,0 +1,7 @@
+## 0.19.10
+**`(fix):`** Replace `unwrap_or_default()` with proper error propagation via `map_err(ApiError::Serialization)?`
+when serializing request bodies with `serde_json::to_value`. Previously, serialization failures
+were silently swallowed and replaced with a default JSON null value. Now they correctly return
+an `ApiError::Serialization` error to the caller.
+
+