Extracting a current user text from BeforeInvocationEvent may not in latest strands framework.

[suresh-bojjam]

With latest strands framework, At below line extracting current user message may not work as BeforeInvocationEvent raised before user input text added to messages.

awesome-ai-apps/course/aws_strands/08_guardrails/guardrails.py

Line 245 in 59d576c

user_input = self._extract_user_input(event)