Allow ruff to auto-fix trailing spaces in multi-line comments

[anoadragon453]

Prior to this change, trailing spaces in a multi-line comment would cause the linting script to error with the following:

➜ ./scripts-dev/lint.sh                  
Linting these paths: synapse docker tests scripts-dev contrib synmark stubs .ci

+ ./scripts-dev/config-lint.sh
+ ruff check --quiet --fix synapse docker tests scripts-dev contrib synmark stubs .ci
W293 Blank line contains whitespace
   --> synapse/storage/databases/main/delayed_events.py:276:1
    |
274 |                 events. If set to false, events which are marked as processed
275 |                 will have their `send_ts` re-checked.
276 |                 
    | ^^^^^^^^^^^^^^^^
277 |                 This is mainly useful for recovering from a server restart;
278 |                 which could have occurred between an event being marked as
    |
help: Remove whitespace from blank line

which I'd have to then fix manually. "Surely ruff can just fix this itself", I thought. And it turns out it can! But said fix is considered unsafe if the trailing spaces are contained within a multi-line string/comment.

Adding this to the list of "safe" fixes produced no ill effects. If someone really wants trailing spaces for some reason, they can add # noqa: W293 after the closing quote of said string to preserve them. Said trailing spaces would have already made ruff error before this change, however. And I see no other mention of W293 (so someone attempting to have trailing spaces) before now. So I think this is a no-brainer to enable.

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]

Reference https://docs.astral.sh/ruff/rules/blank-line-with-whitespace/

[anoadragon453]

I held off on putting the link in here as one is meant to be able to look up the code in the rulebook.

[MadLittleMods]

That's fine but at-least PR review wise, I want to look at it quickly

[anoadragon453]

That's fair! And if one were to add it to a PR self-review comment, they may as well put it in the codebase too. I'll keep that in mind for future PRs.