Update Zod plugin to handle 'guid' string format

Author: mrlubos

.changeset/cyan-boats-type.md

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