aria-practices regression tests are now "headless" by default

Hi aria-practices contributors,

In https://github.com/w3c/aria-practices/pull/1888 we changed the way
regression tests are run by default, from non-headless to headless.
Headless means that the browser is not visible while tests are running.

If you want to opt-in to non-headless, use DEBUG=1 environment variable:

$ DEBUG=1 npm run regression

If you were using CI=1 to run tests in headless mode, you no longer need to
use that environment variable:

$ npm run regression

See updated documentation at
https://github.com/w3c/aria-practices/wiki/Regression-Tests-for-APG-Example-Pages#running-tests

cheers,
-- 
Simon Pieters
Bocoup https://bocoup.com/