CI: MacOS tests failed due to bizarre tar issue with github actions

[joergbrech]

Closes #977

Description

Previously, TiGL-unittests was not executable in the macos-test job. The reason seems to be that the tar archive of the build directory was corrupted. Switching from tar to gtar (GNU tar) works around this issue.

See https://github.com/actions/runner-images/pull/2163 and https://github.com/orgs/community/discussions/24994.

How Has This Been Tested?

CI works again

Screenshots, that help to understand the changes(if applicable):

Not applicable

Checklist:

• [ ] A test for the new functionality was added.
• [x] All tests run without failure.
• [ ] The new code complies with the TiGL style guide.
• [ ] New classes have been added to the Python interface.
• [ ] API changes were documented properly in tigl.h.

[codecov[bot]]

Codecov Report

Merging #981 (db95f76) into master (45a9428) will not change coverage. The diff coverage is n/a.

Additional details and impacted files

[](https://app.codecov.io/gh/DLR-SC/tigl/pull/981?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DLR-SC) ```diff @@ Coverage Diff @@ ## master #981 +/- ## ======================================= Coverage 68.90% 68.90% ======================================= Files 298 298 Lines 26479 26479 ======================================= Hits 18246 18246 Misses 8233 8233 ```

[joergbrech]

@AntonReiswich I suggest squashing the commits before merging for this PR, to avoid cluttering our history.