How to update/upgrade a package using pip?
The way is
pip install <package_name> --upgrade
or in short
pip install <package_name> -U
sudo will ask to enter your root password to confirm the action, but although common, is considered unsafe.
If you do not have a root password (if you are not the admin) you should probably work with virtualenv.
You can also use the user flag to install it on this user only.
pip install <package_name> --upgrade --user
For a non-specific package and a more general solution, you can check out pip-review. A tool that checks what packages could/should be updated.
$ pip install pip-review
$ pip-review --interactiverequests==0.14.0 is available (you have 0.13.2)Upgrade now? [Y]es, [N]o, [A]ll, [Q]uit y