Make the macOS regex allow macosx

[kattouf]

When using build triple names for release assets, there is an issue with macOS assets because the OS name in Swift’s build triples is macosx instead of macos.

Sources for reference:
• List of possible triples in Swift tests
• Article on building Swift executables using triples
• Example of assets named by triples

[autarch]

Hi, thanks for your PR! I'm pretty finicky about my projects (see this blog post for details), so I rarely merge a PR as-is. I can move forward on your PR in one of two ways:

1. I check it out locally, fiddle with it as needed, merge it locally, and simply close this PR. This will preserve at least one commit with your name on it, but the PR will show up as closed in your GitHub stats.
2. If you enable me to push directly to your fork, I can do my fiddling, then force push to your fork and merge the resulting PR. Again, this will preserve at least one commit with your name on it, but you also get credit for the PR merge in your GitHub stats. The only downside is that I will be force pushing directly to your fork.

Please let me know which approach you'd prefer. If I don't hear from you before I get around to working on this PR I'll go with option 1.

Thanks again for your contribution!

[kattouf]

Hi! This PR contains a small amount of work, so I believe the first option works well. Feel free to handle it in a way that’s most convenient for you. 👌

UPD:
I’ve also given you access to my forked edits, if that works better for you.

[autarch]

Thanks again for the PR!