Removed duplicated unit test

[huddeldaddel]

Proposed Changes

This change removes the test case 'should open as BPMN'.
This test case is an exact duplicate of 'should open file' (same file, line 38).

Checklist

To ensure you provided everything we need to look at your PR:

• Brief textual description of the changes present
• Visual demo attached
• Steps to try out present, i.e. using the @bpmn-io/sr tool
• Related issue linked via Closes {LINK_TO_ISSUE} or Related to {LINK_TO_ISSUE}

[nikku]

Thanks, good spot!