Emails from iOS and MacOS clients can often come with size
transformation. This results in a broken layout when sanitizing with Vue
letter.
This PR updates the vue-letter to include the [recent changes made
there](https://github.com/mat-sz/vue-letter/pull/2). And adds the
`transform` and `transform-origin` properties to the allow list
Ref: https://www.caniemail.com/features/css-transform/
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Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>