fix: Correct ansi cell width calculation

[coveralls]

Pull Request Test Coverage Report for Build 3374265869

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 2140989676:	0.0%
Covered Lines:	642
Relevant Lines:	642

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💛 - Coveralls

[github-actions[bot]]

:tada: This PR is included in version 6.8.1 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: