Upgraded packages to use tailwindcss 3

[eugenioenko]

• Upgraded talwindcss to v3
• Updated visuallyHidden component to use sr-only class
• removed purgecss
• updated talwind.config.js to include [content]

---

Breaking Change

The core pkg no longer ships the visually-hidden and js-focus-visible styles. These were previous provided by an css file that Ember CLI would import into your vendor file. These styles are now provided by @frontile/core tailwind plugin.

You also will need to add to your tailwind safelist the following new rules:

{ pattern: /^js-focus-visible/ },
{ pattern: /^sr-only/ },

You can remove the following:

{ pattern: /^visually-hidden/ },

[eugenioenko]

I'm still getting this warning even thought technically content: is set