Description

Introduces 2 env variables to overcome some psutil issue.

PYTEST_MONITOR_FORCE_CPU_FREQ forces pytest-monitor to not compute the cpu frequency and use a default value instead
PYTEST_MONITOR_CPU_FREQ instructs pytest-monitor to consider using this value as a fallback value if it cannot compute the cpu frequency.

Fixes #60

Type of change

[x] 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 not work as expected)
[x] This change requires a documentation update

[x] My code follows the style guidelines of this project
[x] I have performed a self-review of my own code
[x] I have commented my code, particularly in hard-to-understand areas
[x] I have made corresponding changes to the documentation
[ ] My changes generate no new warnings
[x] I have added tests that prove my fix is effective or that my feature works
[x] New and existing unit tests pass locally with my changes (not just the CI)
[x] Any dependent changes have been merged and published in downstream modules
[x] I have updated the changelog
[x] I have labeled my PR using appropriate tags (in particular using status labels like Status: Code Review Needed, Business: Test Needed or Status: In Progress if you are still working on the PR)