Release 0.76.8

See https://docs.lamin.ai/changelog#db-0-76-8

What's Changed

• 📝 Use unload in notebooks by @Koncopd in #1946
• 🐛 Fix unload by @Koncopd in #1947
• ✨ Store artifacts under their virtual keys in cache by @Koncopd in #1954
• 💚 Better cleanup in unit-core tests by @Koncopd in #1957
• 🚸 No traceback for invalid arguments by @falexwolf in #1956
• 🐛 Ensure is_latest is set to False in previous version if matching on artifact.key by @falexwolf in #1958
• 🐛 Fix .save writing to current folder for new versions of an Artifact by @Koncopd in #1959

Full Changelog: 0.76.7...0.76.8