feat: add log level from env vars

Description

Add LOG_LEVEL env var as an optional, if it's not passed the log level will be error as default.

Related issues

Testing

Checklist

• I have updated the documentation (if necessary)
• I have added unit tests for new functionality (if applicable)
• My code follows the style guidelines of this project
• I have tested this code on my local machine before submitting this MR

Reviewers

@alexey.lunin @boyan.tsolov

Additional Notes

Closes #83 (closed)