Hot v2.6.5

What's Changed

• ci: cross-platform tests on macOS and Windows by Curtis Summers (@csummers) in #74
• Add atomic store put-if-missing by Curtis Summers (@csummers) in #75
• github pkg 1.0.0 by Curtis Summers (@csummers) in #76

Full Changelog: v2.6.4...v2.6.5