Re-usable Complement GitHub CI workflow

[MadLittleMods]

As suggested by @anoadragon453,

Re-usable Complement GitHub CI workflow

Dev notes

• https://docs.github.com/en/actions/how-tos/reuse-automations/reuse-workflows

Pull Request Checklist

• Pull request is based on the develop branch
• Pull request includes a changelog file. The entry should:
  • Be a short description of your change which makes sense to users. "Fixed a bug that prevented receiving messages from other servers." instead of "Moved X method from EventStore to EventWorkerStore.".
  • Use markdown where necessary, mostly for code blocks.
  • End with either a period (.) or an exclamation mark (!).
  • Start with a capital letter.
  • Feel free to credit yourself, by adding a sentence "Contributed by @github_username." or "Contributed by [Your Name]." to the end of the entry.
• Code style is correct (run the linters)

[MadLittleMods]

I've tried out use_latest_deps and use_twisted_trunk in some CI runs and they appear to work. I don't know if the versions are actually being changed as expected.

• fa08b98 -> https://github.com/element-hq/synapse/actions/runs/22782133537
• f4e4152 -> https://github.com/element-hq/synapse/actions/runs/22841316669