chore: Bump version to 21.1.0 (#297)

## What's Changed

This is a minor release because there is no backward incompatible
change.

#283.
diff --git a/package.json b/package.json
index 9f8fd65..c9a4ea8 100644
--- a/package.json
+++ b/package.json
@@ -114,5 +114,5 @@
   "engines": {
     "node": ">=20.0"
   },
-  "version": "21.0.0"
+  "version": "21.1.0"
 }