Revert "CI: Don't rely on CIRCLE_TAG variable"
Revert "CI: Don't rely on CIRCLE_TAG variable"

This reverts commit 39909e1af0b315974b4201412b2cb1dcaa9684ed.

The variable *does* work if it's triggered correctly.

threema-ch/threema-web,threema-ch/threema-web,threema-ch/threema-web,threema-ch/threema-web,threema-ch/threema-web