🚀 deploy v0.3.0b

What's Changed

• ✨ postgresql migration by @tteokgook1 in #256
• 🚀 deploy v0.3.0b by @tteokgook1 in #257
• 🚑 hotfix for v0.3.0b by @tteokgook1 in #259

Full Changelog: v0.3.0a...v0.3.0b