Fix typo in authenticate

[DongSeonYoo]

Are you implementing a new feature?

• no

Is this a security patch?

• no

Checklist

• I have read the CONTRIBUTING guidelines.
• I have added test cases which verify the correct operation of this feature or patch.
• I have added documentation pertaining to this feature or patch.
• The automated test suite ($ make test) executes successfully.
• The automated code linting ($ make lint) executes successfully.

[DongSeonYoo]

I will close it because the existing pr exists.