Drop support for Python 2.7

[mdmintz]

Drop support for Python 2.7

It's time to drop support for Python 2.7. This day has been coming for awhile.

For a long time, I've continued maintaining support for it, but now it's just holding me back, and making SeleniumBase more complicated than it needs to be.

SeleniumBase has been extending Python 2.7 exactly 3 years past its official end-of-life date:

• DEPRECATION: Python 2.7 reached the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no longer maintained. pip 21.0 will drop support for Python 2.7 in January 2021. More details about Python 2 support in pip can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support pip 21.0 will remove support for this functionality.

[mdmintz]

Released in 4.11.0 - https://github.com/seleniumbase/SeleniumBase/releases/tag/v4.11.0