use different artifact names

[e-perl-NOAA]

Concisely describe what has been changed/addressed in the pull request.

For some reason, the build-artifact workflow is no longer uploading all of the executables from the different operating systems to the same artifact named "ss3" (see artifact from PR #542). I have changed the workflow to upload an artifact for each OS, which is working (see workflow run here).

First seen in PR #541 by @iantaylor-NOAA.

What tests have been done?

Where are the relevant files?

• [x] No test files are required for this pull request. -->

What tests/review still need to be done?

None.

Is there an input change for users to Stock Synthesis?

• [x] No, there was no input change. -->

Additional information (optional).

[e-perl-NOAA]

I think so, I don't know why the upload-artifacts action now doesn't want to upload artifacts in a folder under the same name anymore but this should allow all artifacts to upload now.