Currently there seems to be no version independent URL for the latest phar release. You have to go to "releases" and select the latest version and receive something like https://github.com/Mayflower/PHP_CodeBrowser/releases/download/1.1.1/phpcb-1.1.1.phar
Other tools like phpunit provide a unique URL which always points to the latest release, like
https://phar.phpunit.de/phpunit.phar
This would give the possibility in certain scenarios (that do not use composer) to receive the latest phar release of PHP CodeBrowser.