ci: add version 1.2.1 to release-please manifest

[aj3sh]

Description

The newer version of release-please (v16) doesn't track the previous version from the Github releases. Therefore, the release PR for the next release version becomes v1.0.0. See PR https://github.com/opensource-nepal/node-nepali-datetime/pulls

I have added the current version to the .release-please-manifest.json file to fix this issue.

Related Issue

N/A

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
• Other (CI)

Checklist

• 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.
• 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.