Release v0.3.0

Awesome release with serialization, finally! 🤞 ❤️
Ktoml now supports it!

What's Changed

• Implement encoding by @NightEule5 in #153
• Adding test for required fields by @akuleshov7 in #152
• Upgraded version of kotlin and serialization by @nulls in #154

New Contributors

• @nulls made their first contribution in #154

Full Changelog: v0.2.13...v0.3.0