Fix tests

Description

Commits

• Fix calculate_co2 test

• Prevent meteo_data_handler test to override a reference co2 file

Related Issue

Closes #126 (closed) and #129 (closed)

How Has This Been Tested?

Tested locally and in CI

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.