refactor: update `blas/ext/base/dsnannsumors`

[GittyHarsha]

Resolves #1491

Description

What is the purpose of this pull request?

This pull request:

• Refactors blas/ext/base/dsnannsumors to follow current project conventions

Related Issues

Does this pull request have any related issues?

This pull request:

• resolves #1491
• progresses #1152

Questions

Any questions for reviewers of this pull request?

No.

Other

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No.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• [x] Read, understood, and followed the contributing guidelines.

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@stdlib-js/reviewers

[GittyHarsha]

@Planeshifter, please review my PR. Thanks!

[GittyHarsha]

Any updates?

[GittyHarsha]

Thank you for your contribution @GittyHarsha!

PR looked very good; I just reverted the changes to the copyright years, which we do not update when files are edited.

Thanks! I hope this will be my first contribution.