DateTime fix typo in lambda example (#4678)

fixed copy&paste typo

Author: matthias-m

components/datetime/index.rst

@@ -288,7 +288,7 @@ For more complex use cases, several methods are available for use on datetimes f
 
       // Within lambda, set the datetime to 2024-12-31 12:34:56
       auto call = id(my_datetime).make_call();
-      call.set_date("2024-12-31 12:34:56");
+      call.set_datetime("2024-12-31 12:34:56");
       call.perform();
 
   Check the API reference for information on the methods that are available for