Added my details to the list contributors.yaml

[nitish-awasthi]

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Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• The title of my pull request is a short description of the requested changes.
• I have added the label enhancement to my pull request.