Add changeset for the zod guid implementation

Author: erikwski

.changeset/cyan-boats-type.md

@@ -2,4 +2,4 @@
 "@hey-api/openapi-ts": patch
 ---
 
-**plugin(zod)**: add Resolvers API
+**plugin(zod)**: support OpenAPI `guid` string format in Zod v4 and Zod Mini outputs