Add package creation for MacOS

[terjekv]

No description provided.

[kniec]

AWS has mac1.metal instances now... :)

[boegel]

@bedroge Failing tests look unrelated to the changes in this PR?

[bedroge]

@boegel The Centos 8 failures/timeouts have been solved in #57.

But I don't understand the issue with build-linux-packages: fpm gave some weird error

/usr/local/bundle/gems/fpm-1.11.0/lib/fpm/package/deb.rb:495:in `block in output': uninitialized constant FPM::Package::Deb::Zlib (NameError)
171	from <internal:kernel>:90:in `tap'
172	from /usr/local/bundle/gems/fpm-1.11.0/lib/fpm/package/deb.rb:494:in `output'
173	from /usr/local/bundle/gems/fpm-1.11.0/lib/fpm/command.rb:487:in `execute'
174	from /usr/local/bundle/gems/clamp-1.0.1/lib/clamp/command.rb:68:in `run'
175	from /usr/local/bundle/gems/fpm-1.11.0/lib/fpm/command.rb:574:in `run'
176	from /usr/local/bundle/gems/clamp-1.0.1/lib/clamp/command.rb:133:in `run'
177	from /usr/local/bundle/gems/fpm-1.11.0/bin/fpm:7:in `<top (required)>'
178	from /usr/local/bundle/bin/fpm:23:in `load'
179	from /usr/local/bundle/bin/fpm:23:in `<main>'

This worked fine with the last commits... and it doesn't look like the fpm action has been changed in the meantime (fpm version is still the same too)....

[bedroge]

jordansissel/fpm#1739
https://github.com/jordansissel/fpm/blob/v1.11.0/lib/fpm/package/deb.rb#L495

I have no clue how this could have worked before...

[bedroge]

The CI for building the packages has been fixed, see #64.
Rerunning the tests now...

A fix for the failing Centos 8 tests is included in this PR:
#57

[bedroge]

Hmm, I think this part was already included in #48, so I guess we can close this PR.

[bedroge]

See for instance this action (triggered by PR #57) for a macOS package:
https://github.com/EESSI/filesystem-layer/actions/runs/408367869
We can make a new release soon, so that we have a versioned package for macOS.

Closing this PR.