Automatically update copyright year every Jan 1st

[MetRonnie]

These changes partially address #171

This GitHub Actions workflow will create a PR with the updated copyright year in README.md at 12:00 UTC every new year's day.

This sort of workflow also serves as a proof-of-concept for other automation to be addressed from #171

Demo:

• The workflow: https://github.com/MetRonnie/spork/runs/843244544?check_suite_focus=true
• The PR it created: https://github.com/MetRonnie/spork/pull/5

[MetRonnie]

Good point, at the very least this can act as a PoC