vueunit.yml failing, check and re-enable when migrating to Vue 3

[sampsapenna]

Describe the bug

vueunit.yml uses testing-library, which is no longer supported for Vue 2. This means that, if we are to update to Vue 2.7, we need to deprecate this workflow until move to Vue 3. Migrating to Vue 3 via Vue 2.7 is a simpler alternative, as 2.7 backports a lot of the features provided in Vue 3 – e.g. the composition API as built-in.

To Reproduce

Steps to reproduce the behaviour:

cd swift_browser_ui_frontend
npm i
npm test

Expected behavior

The jest tests run properly.

Screenshots

Additional context

This issue should resolve itself when we migrate to Vue 3, since the library should support it.