[eslint] - enable `no-unsafe-finally`

[phenomnomnominal]

Just seem an issue in some async/await code that that would've been prevented if the https://eslint.org/docs/rules/no-unsafe-finally has been enabled! Are there any downsides to this rule?

[kirbysayshi]

This seems reasonable to me. Would you consider submitting a PR (unless someone else objects, of course)?