Fix of failed Screenshot Test in report-ng-test

[clemensgrosse]

Description

Fix of failing report test concerning screenshots of collected assertions. Test method test_multipleScreenshotsShown, which checks existence of multiple screenshots, now verifies this for test_takeScreenshotViaCollectedAssertion_fails, too.

Fixes issue #390

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• [ x] My code follows the style guidelines of this project
• [x ] I have performed a self-review of my own code
• [ x] I have commented my code, particularly in hard-to-understand areas
• [ x] My changes generate no new warnings
• [ x] New and existing tests pass locally with my changes
• [x ] Any dependent changes have been merged and published in downstream modules