scripts: loglevel warning message fix

[maxemann96]

Description

If the loglevel is invalid (for example DEBUG) it will print

[ WARNING ] Log level 'info' is invalid (falling back to default 'info')

But the correct message would be

[ WARNING ] Log level 'DEBUG' is invalid (falling back to default 'info')

Fixes no open issue.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (non-breaking change that does improve existing functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project

• I have performed a self-review of my own code

• I have commented my code, particularly in hard-to-understand areas

• I have made corresponding changes to the documentation (README.md or the documentation under docs/)

• If necessary I have added tests that prove my fix is effective or that my feature works

• New and existing unit tests pass locally with my changes

• I just used the github online editor to propose this change. No local test.

[georglauterbach]

Thank your for your contribution and for fixing this issue!