Automate the process of updating the license

As of now, we have a manual process of updating the license at least updating the year.

Example: https://github.com/chaoss/grimoirelab-perceval/commit/076953e95735401b4d9266562f9ae406a30751a0

We can automate this as this applies to all the components in the grimoirelab. Maybe a small script that updates the year, which can be executed yearly once.

This can be extended to updating the Authors in the license too.

Inspired by https://github.com/Bitergia/prosoul/issues/13#issuecomment-591940810. :slightly_smiling_face: