[PERL] Fix bug on test script

Created by: thomasphansen

This fixes a small bug in a perl test script, as mentioned in PR #12871...

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mentioned in merge request !12871 (closed)

added Client: Perl Enhancement: CI/Test labels

changed milestone to %6.1.0

The fix looks good and tests passed via https://app.travis-ci.com/github/OpenAPITools/openapi-generator/builds/253548183.

Thanks for the contribution. Have a nice weekend.

closed