AO3-7594 Update html in invalid_signup_notification.html.erb mailer

[delphi121]

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• Have you added tests for any changed functionality?
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  as the first thing in your pull request title (e.g. AO3-1234 Fix thing)
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Issue

https://otwarchive.atlassian.net/browse/AO3-7594

Purpose

Updates the HTML to be consistent with the rest of the mailers, by moving the ul element out of the p element.

Testing Instructions

A visit to the mailer preview at https://test.archiveofourown.org/rails/mailers/gift_exchange_mailer/ will confirm the HTML cleanup still displays the list element as intended.

Credit

bowekatan
She/her

[sarken]

Hi, bowekatan!

Thank you so much for this pull request. Someone will be along to review it soon.

In the meantime, I've assigned the Jira issue to you and set its status to In Review, so no one mistakenly creates a duplicate pull request. I've also given your account permission to comment on, assign, and transition issues in the future.

Thanks again for contributing! If you have any questions, you can contact us at otw-coders@transformativeworks.org.

[ASalbenblatt]

Just one small formatting issue :)

[sarken]

If you have time to action the comment from @ASalbenblatt, that would be great! However, it's not blocking, so I'm going to mark this approved.

[ASalbenblatt]

Looks great, thanks!!