Fix coverage report

[dalonsoa]

Description

When pytest is run, a coverage report should be generated in reports/coverage but the path indicating which folder should be observed to calculate the coverage was wrongly set.

To be reviewed and merged after #52

Fixes # None

Type of change

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist

• Make sure you've run the pre-commit checks: $ pre-commit run -a
• All tests pass: $ poetry run pytest

Further checks

N/A

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works