Fix path name in PR builder
Fix path name in PR builder

The task files now come form an artifact called "cli-master" not from an
artifact called "cli".

Co-authored-by: Tom Viehman <ef9e7682e71c138189ac51545830b782ff2b8b7d@pivotal.io>

cloudfoundry/cli,cloudfoundry/cli,cloudfoundry/cli