ci: update copyright year as part of CMake Nightly Date Stamp

Extend commit 0f82d07266 (ci: add job to update CMake Nightly Date
Stamp, 2024-12-17) to update the year range in `Copyright.txt` on
January 1 so we don't have to update it manually once per year.
Our `CMake.Copyright` test verifies that these match.
2 files changed