Fix regression with CI variable

[matteius]

The issue

Fixes #5554

The fix

Use pipenv utility for reading and checking the env variable but doesn't require its truthyness.

The checklist

• Associated issue
• A news fragment in the news/ directory to describe this fix with the extension .bugfix.rst, .feature.rst, .behavior.rst, .doc.rst. .vendor.rst. or .trivial.rst (this will appear in the release changelog). Use semantic line breaks and name the file after the issue number or the PR #.