Added the feature of auto commenting on merged pr

[suhanipaliwal]

Description

I have added the file auto-comment-pr-merge.yml in the .github/workflows directory. This will add the feature of auto commenting as soon as a pull request is merged in your repository. This reduces the workload on project maintainers.

Type of PR

• [ ] Bug fix
• [x] Feature enhancement
• [ ] Documentation update
• [ ] Other (specify): _______________

Checklist:

• [x] I have performed a self-review of my code
• [x] I have read and followed the Contribution Guidelines.
• [x] I have tested the changes thoroughly before submitting this pull request.
• [x] I have provided relevant issue numbers, screenshots, and videos after making the changes.
• [x] I have commented my code, particularly in hard-to-understand areas.

Additional context:

Please merge this pull request and add the labels of gssoc and level1 on this pr as per gssoc guidelines.