Add vote datetime to `vote` DB model

[tohuynh]

Feature Description

A clear and concise description of the feature you're requesting. Add vote datetime field to the vote DB model https://github.com/CouncilDataProject/cdp-backend/blob/main/cdp_backend/database/models.py#L698

Use Case

Please provide a use case to help us understand your request in context. The front end wants to be able to sort a person's voting record by vote datetime.

Solution

Please describe your ideal solution.

Alternatives

Please describe any alternatives you've considered, even if you've dismissed them.