CI - try security-checker v5 on 7.1 build
CI - try security-checker v5 on 7.1 build

v5 works in 7.0
https://travis-ci.org/EdgedesignCZ/phpqa/jobs/552114088#L661

v6 causes `SSL connect error` in 7.1
https://travis-ci.org/EdgedesignCZ/phpqa/jobs/552114089#L910
EdgedesignCZ/phpqa,EdgedesignCZ/phpqa