pip: Removing duplicated names in AUTHORS.txt

I noticed that a few people would get duplicated names in AUTHORS.txt. I think it would be a good idea to avoid duplication in the AUTHORS.txt file if possible.

I’ll post the following on this issue if @pypa/pip-committers think we should de-duplicate it…

To the following, I ask: Which email do you want associated with your name in AUTHORS.txt?

@atdaemon: anish.tambe@yahoo.co.in or anish.tambe@yahoo.in
@vartec: b.ogryczak@gmail.com or bartek@eventbrite.com
@kuzmiigo: igor@qubit.com or kuzmiigo@gmail.com
@luojiebin: luo.jiebin@qq.com or luojiebin@users.noreply.github.com
@StephanErb: github@stephanerb.eu or stephan@dev.static-void.de 
@takluyver: thomas@kluyver.me.uk or takowl@gmail.com