Remove posix only unittest relying on presence of unzip untility.

[ghost]

Even on posix systems you cannot rely on unzip being installed. In such cases, the unittest will fail, but should not fail.

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[CyberShadow]

I can't see this as a good idea. The test suite of most software is going to have special requirements on the host it runs on. We definitely shouldn't remove tests just because there exist systems out there that cannot run them.

[atilaneves]

At most, this should be not run on systems that can't, but definitely not deleted.

[ghost]

I still feel unhealthy with this, but I believe you, that it is ok. I added the check proposed by cybershadow though.