Fix Action runner issues

[robertbartel]

Fixing some issues that were causing runners to not successfully pass checks.

Removals

• Removed the non-working add_to_project workflow, which attempts to perform automation that is not meaningfully used anyway

Changes

• Modified unit testing action to use ubuntu-latest and macos-latest, rather than specific version labels (the previous labels had become outdated)
• Fixed issues in Mac runner integration tests related to integration dependency building (Fortan compiler version and CMake policy version min for Sloth)

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows project standards (link if applicable)
• Passes all existing automated tests
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future todos are captured in comments
• Visually tested in supported browsers and devices (see checklist below 👇)
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)
• Reviewers requested with the Reviewers tool ➡️

Testing checklist

Target Environment support

• Windows
• Linux
• Browser

Accessibility

• Keyboard friendly
• Screen reader friendly

Other

• Is useable without CSS
• Is useable without JS
• Flexible from small to large screens
• No linting errors or warnings
• JavaScript tests are passing

[aaraney]

Looks great! Thanks, @robertbartel!