stop data attributes from being stripped

[CriticalRespawn]

This PR (hopefully) fixes an issue raised in #9500 where data-* attributes get stripped from the HTML on AMP pages.

This PR simply adds data-* to the allowedAMPAttributes array.

[aileen]

Thanks for the PR @CriticalRespawn!

The changes look fine and also work as expected. 👍

If you want to look into doing more PRs for Ghost, you can check out our guidelines and docs: https://docs.ghost.org/docs/contributing#section-submitting-pull-requests . They helped me a lot! 😉

[aileen]

@kirrg001 I don't know why this is happening here, but Node 4 seems to have a problem with knex-migrator: https://travis-ci.org/TryGhost/Ghost/jobs/353644294#L764 and therefore Travis is failing.

I was facing the same problems locally, when I tried to debug this. I couldn't even run knex-migrator init.

[kirrg001]

@AileenCGN Why do you think it's knex-migrator? 🤔

SyntaxError: Unexpected token {
at exports.runInThisContext (vm.js:53:16)
at require (internal/module.js:12:17)
at Object. (core/server/lib/mobiledoc/cards/index.js:2:12)

[aileen]

Why do you think it's knex-migrator?

Because it happened as well locally when I tried to reproduce this in Node 4 and knex-migrator init failed for the same reason. The error log looked a bit different (still Unexpected token, but failing in knex-migrator).