Fix the method for detecting unread messages for Google Chat

[Shampra]

Pre-flight Checklist

Please ensure you've completed all of the following.

• [x] I have read the Contributing Guidelines for this project.
• [x] I agree to follow the Code of Conduct that this project adheres to.
• [x] I updated the version package Updating

Description of Change

Change the method for detecting unread messages, because using div classes is broken every time Google chat is updated (this is currently the case)

[Shampra]

Same checks in my fork, with the fixed scripts\package.json, works... 😖

[vraravam]

@Shampra - please review all changes (including formatting changes) before raising any PR. This PR caused the build to break the nightly run.