[automated-commits] Add update-timings

Summary: Enables us to automate the updating of timing.json

Test Plan:

COMMIT_TYPE=update-timings ./automated-commits.sh

I didn't have python3-zmq installed on my new machine, so it failed as expected. Run again after installing and it succeeded.

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D5337