docs(event-handler): fixed SchemaValidationMiddleware link (#3247)

change relative link

Author: jvnsg

docs/core/event_handler/api_gateway.md

@@ -575,7 +575,7 @@ These are native middlewares that may become native features depending on custom
 
 | Middleware                                                                                           | Purpose                                                                                                                                 |
 | ---------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------- |
-| [SchemaValidationMiddleware](/api/event_handler/middlewares/schema_validation.html){target="_blank"} | Validates API request body and response against JSON Schema, using [Validation utility](../../utilities/validation.md){target="_blank"} |
+| [SchemaValidationMiddleware](/lambda/python/latest/api/event_handler/middlewares/schema_validation.html){target="_blank"} | Validates API request body and response against JSON Schema, using [Validation utility](../../utilities/validation.md){target="_blank"} |
 
 #### Being a good citizen