Update changelogs from fern repo (#5222)

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

Author: fern-support

fern/products/sdks/generators/typescript/changelog/2026-04-29.mdx

@@ -0,0 +1,6 @@
+## 3.66.4
+**`(fix):`** Fix undiscriminated-union query parameters so the list variant is sent as
+repeated keys (`?key=a&key=b`) instead of a URL-encoded JSON blob. Mirrors
+the Go fix in #15526.
+
+