sed -z is not available on MacOS

[elidhu]

I would suggest either:

• changing to sed s/$/ /
• conditional compilation
• not using sed!

Note that this affects your unit tests and the regressing test for shell, including the regression test checker

[FauconFan]

This asks a bigger problem, such as testing in a MacOS like environment, currently only ubuntu is tested. See #5 for Windows. I'll mark this as Help wanted if anyone wants to extend the CI pipeline to MacOS.

Ty for reporting this.