build: replace deprecated coveralls with supported coveralls-next

[mixator]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

https://www.npmjs.com/package/coveralls-next are actively maintained rewrite of the original coveralls library for Node.js. Built for Node.js 20+ with modern dependencies and improved reliability.

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

[coveralls]

Pull Request Test Coverage Report for Build 230669

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 89.829%

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Totals
Change from base Build de840762-4bfe-4770-992b-5e40c0894ecb:	0.0%
Covered Lines:	7463
Relevant Lines:	8308

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💛 - Coveralls

[mixator]

@kamilmysliwiec I've resolved conflicts and put exact version