Support for TLS 1.0 and 1.1 was dropped for PyPI. If your system does not use a more recent version, it could explain your error.
Could you try reinstalling pip system-wide, to update your system dependencies to a newer version of TLS?
This seems to be related to Unable to install Python libraries
See Dominique Barton's answer:
Apparently pip is trying to access PyPI via HTTPS (which is encrypted and fine), but with an old (insecure) SSL version. Your system seems to be out of date. It might help if you update your packages.
On Debian-based systems I'd try:
apt-get update && apt-get upgrade python-pip
On Red Hat Linux-based systems:
yum update python-pip # (or python2-pip, at least on Red Hat Linux 7)
On Mac:
sudo easy_install -U pip
You can also try to update openssl separately.
