fix: allow to open links in email preview

[felixmosh]

Checklist

• I have ensured my pull request is not behind the main or master branch of the original repository.
• I have rebased all commits where necessary so that reviewing this pull request can be done without having to merge it first.
• I have written a commit message that passes commitlint linting.
• I have ensured that my code changes pass linting tests.
• I have ensured that my code changes pass unit tests.
• I have described my pull request and the reasons for code changes along with context if necessary.

closes #36

Chrome blocks clicking on links inside an iframe with sandbox attribute without allow-popups.

[titanism]

preview-email v3.0.20 released to npm

https://github.com/forwardemail/test-preview-emails-cross-browsers-ios-simulator-nodejs-javascript/releases/tag/v3.0.20