v5.0: macos support

What's Changed

• feat: enable dependabot for github-actions ecosystem by @wdconinc in #26
• Re-enable experimental support for cvmfs on macos runners by @vvolkl in #28
• CVMFS mac support now in prod; use homebrew to install by @vvolkl in #31
• macos: move sleep into setup by @vvolkl in #32

Full Changelog: v4...v5.0