Add testing on JDK 16 and 17

[alexvanyo]

Updates CI to test on JDK 16 and JDK 17 as well.

[github-actions[bot]]

🧛 Project Code Coverage: 97.78%

Coverage of Modified Files:

File	Coverage

Modified Files Not Found In Coverage Report:

build.gradle.kts ci.yml

Codebase cunningly covered by count Shroud 🧛

Generated by :no_entry_sign: Danger

[alexvanyo]

Thanks @byencho !