This release upgrades Kintsugi from 1.8.1 to 1.9.0

Major changes

• Simplify Vault reward supply distribution

Release notes

• https://github.com/interlay/interbtc/releases/tag/1.9.0
• https://github.com/interlay/interbtc/releases/tag/1.8.2

Code changes

https://github.com/interlay/interbtc/compare/1.8.1...1.9.0