Fix `coveralls` by changing the extension to `.lcov`

[IvanIsCoding]

I have no idea why but our Coveralls integration started complaining about lcov files with .info, so I switched to .lcov

[coveralls]

Pull Request Test Coverage Report for Build 9183064992

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 96.508%

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Totals
Change from base Build 9139666696:	0.03%
Covered Lines:	16750
Relevant Lines:	17356

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💛 - Coveralls