Update kotlin to v1.8.21 (#14)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

gradle/libs.versions.toml

@@ -1,5 +1,5 @@
 [versions]
-kotlin = "1.8.0"
+kotlin = "1.8.21"
 
 [libraries]
 inquirer = "com.github.kotlin-inquirer:kotlin-inquirer:0.1.0"