fix: prevent duplicate step execution in GroupChatManager

[UtkarshMishra-Microsoft]

Purpose

This PR addresses a critical issue where certain steps (e.g., background check) were being executed multiple times when approved quickly in succession. It introduces an asyncio.Lock mechanism to ensure only one execution per step, preventing race conditions.

Does this introduce a breaking change?

• Yes
• No

How to Test

• Get the code

git clone [repo-address]
cd [repo-name]
git checkout [branch-name]
npm install

• Test the code

What to Check

Verify that the following are valid

• ...

Other Information