Bug 34911: Test files from HEAD instead of 'master'

Bug 34911: Test files from HEAD instead of 'master'

Since bug 34303 the test suite (when ran on jenkins) is no longer testing Perl::Critic

koha_1       | fatal: Not a valid object name master
koha_1       | [14:58:14] t/00-testcritic.t

We are not cloning the whole repo and "master" is not available. Additionally we do not want to test master's files on stable branches anyway...

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>