Bump version to v5.2.1 (#632)

This PR bumps the version to v5.2.1 using npm version patch.

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Kenneth Sinder <[email protected]>

Author: github-actions[bot]

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@notionhq/client",
-  "version": "5.2.0",
+  "version": "5.2.1",
   "description": "A simple and easy to use client for the Notion API",
   "engines": {
     "node": ">=18"