Update python-prompt-toolkit to 3.0.5 and remove python2 support

Summary:
Full changelog here

Python2 support isn't used by any of existing packages in the repository.

Signed-off-by: Algent Albrahimi <algent@protonmail.com>

Test Plan: Run a few python scripts using spyder3.

Reviewers: Triage Team, JoshStrobl

Reviewed By: Triage Team, JoshStrobl

Subscribers: JoshStrobl

Differential Revision: https://dev.getsol.us/D9269