Auto commenting feature added for merged prs

[suhanipaliwal]

Related Issue

Fixes #49

Description

I have added auto-comment-on-pr-merge.yml in .github/workflows directory. This file will add the feature of auto commenting when a pr is merged.

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.

[suhanipaliwal]

Please add the label of level1 and gssoc on this pull request and assign me this pr as per gssoc guidelines.