feat(ci): add prettier check on ci

[rubiin]

Description

adding a Prettier check to our GitHub Actions workflow. This will ensure that code formatting is consistently applied before changes are merged into our codebase.

Related Issue

closes https://github.com/opensource-nepal/node-nepali-datetime/issues/58

Type of Change

Please mark the appropriate option below to describe the type of change your pull request introduces:

• [ ] Bug fix
• [ ] New feature
• [ ] Enhancement
• [ ] Documentation update
• [ ] Refactor
• [x] Other (ci)

Checklist

• [x] I have used semantic commit messages. Examples: "fix: Fixed foobar bug", "feat(accounts): Added foobar feature".
• [ ] I have added/updated the necessary documentation on README.md.
• [ ] I have added appropriate test cases (if applicable) to ensure the changes are functioning correctly.
• [x] My pull request has a clear title and description.

Additional Notes

[Add any additional notes or context that you think the reviewers should know about.]

By submitting this pull request, I confirm that I have read and complied with the contribution guidelines of this project.

[aj3sh]

Please update the Description and Related Issue section of this PR.