pip 21 heads-up (Python 2 support gone)

Hello Fellow OpenStackers, Please notice pip 21 was released just yesterday. It means Python 2 is no longer supported. Upgrading pip to latest on Python 2 may render pip unusable (as ancient pip may not consider 21 an unsupported version and install it nonetheless). Similarly, using default get-pip.py on Python 2 no longer works. There is, however, https://bootstrap.pypa.io/2.7/get-pip.py for those that want to use get-pip.py on Python 2. Kind regards, -yoctozepto