[e.cash] Update header for 2024

Summary:
This repo had a headerArray with variable calc that was not being used. Implement it.

Run eslint --fix . to update all headers in repo.

Test Plan: Confirm change is only to commented headers and year is correct

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D15269