Update usage of deprecated release.title in release script

[anoadragon453]

Fixes the following warnings when running the release script:

Publish release v1.144.0rc1 on GitHub? [Y/n]:
/home/work/code/synapse/./scripts-dev/release.py:452: DeprecationWarning: Use name instead
  if release.title == tag_name:
/home/work/code/synapse/./scripts-dev/release.py:457: DeprecationWarning: Use name instead
  assert release.title == tag_name
/home/work/code/synapse/./scripts-dev/release.py:464: DeprecationWarning: Use name instead
  name=release.title,

This was deprecated in PyGitHub v2.8.0: PyGithub/PyGithub#3346

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)

[devonh]

Nice!