Fix typo sample.json

[Sandeep-FED]

• New sample
• Bug fix/update
• Related issues: mentioned in Sample Missing from Adoption Sample Solution Gallery Under My Contributions #5438

What's in this Pull Request?

This PR is to update GitHub username in sample.json author details for two of my samples.

[github-actions]

Validation failed!

File: samples/react-engage-hub/assets/sample.json

• Invalid value 'https://github.com/Azure/azure-sdk-for-js/tree/main/sdk/openai/openai.png' for author's 'pictureUrl' property: The provided URL is not responding correctly!

[github-actions]

Sample PR validation for #5468

⚠️ Validation status: warnings

We automatically validate all pull requests against our contribution guidance to ensure that all samples provide a consistent experience to our community.

In order to merge this PR in a timely manner, the following criteria must be met:

Validation	Status
Pull request affects only one folder	⚠️ Warning
Sample folder name follows naming convention	✅ Succeeded
Sample requires a .nvmrc file	⚠️ Warning
Sample requires a README.md	⚠️ Warning
Sample requires a screenshot .png in assets folder	⚠️ Warning
No .sppkg file	✅ Succeeded
No node_modules folder	✅ Succeeded
No lib folder	✅ Succeeded

@Sandeep-FED please address the above issues and push new changes to this branch.
For more information, see the contribution guidance.

[hugoabernier]

Many thanks @Sandeep-FED for your update! Much appreciated!.

Thank you for sharing your sample with others - you rock! 👏🥇👩‍💻