Reminder:
Once the Travis image for PHP 7.3 has been updated to a version of PHPUnit which includes a code coverage driver, the "high" code coverage build should be changed from PHP 7.2 to PHP 7.3.

It would have been nice to move the coverage builds onto 7.3 at this time as that should raise the coverage a little as the PHP 7.3 specific code in the NewFlexibleHeredocNowdoc sniff should then show as covered.
However, that is not yet possible at this time as there is no code coverage driver available for PHP 7.3 in the PHPUnit version included on the PHP 7.3 Travis images at this time.
See https://travis-ci.org/jrfnl/PHPCompatibility/jobs/465544658#L808

From: #764