Fix poetry.lock for dependabot (#237)

Fixes the following dependabot error:

    {"data":{"error-type":"dependency_file_not_parseable","error-details":{"file-path":"/poetry.lock","message":"/poetry.lock not parseable"}},"type":"record_update_job_error"}
    {"data":{"base-commit-sha":"459f7d2981574221893752f788fdd58765a95c05"},"type":"mark_as_processed"}