/client/versions: Advertise MSC4076: Add disable_badge_count to pusher configuration

[manuroe]

so that we can use MSC4076: Let E2EE clients calculate app badge counts themselves (disable_badge_count).

I was not aware of this need when I submitted #17975.

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)

[reivilibre]

(not sure about this; this may be valid but it's not mentioned on the MSC, Manu is looking into it. Possibly, this should be merged but needs to be mentioned on the MSC.)