[email-rotation] use list/dict instead of typing; NFCI

[gburgessiv]

Direct use of list/dict is preferred, and something I learned about when I'd half-written this. Didn't realize I left these instances initially.

[Copilot]

Pull Request Overview

This PR modernizes type annotations by replacing typing.Dict and typing.List with the built-in dict and list types, which are preferred in Python 3.9+. The change simplifies imports and aligns with current Python typing best practices.

• Removed Dict and List imports from the typing module
• Updated all type annotations to use lowercase dict and list instead of their typing counterparts

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[gburgessiv]

(I assume postcommit review policies apply here, and this is really trivial + the tests pass, so...)

[kbeyls]

looks fine to me, consider this postcommit reviewed :) (But I'm not a python expert, I'm trusting you and copilot that it's better not to use typing.Dict and typing.list, but instead use dict and list types.