Update kotlin monorepo to v1.9.21 (#128)

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

Author: renovate[bot]

gradle/libs.versions.toml

@@ -13,7 +13,7 @@ androidx-sqlite = "2.4.0"
 androidx-test-ext = "1.1.5"
 
 jetbrains-dokka = "1.9.10"
-jetbrains-kotlin = "1.9.20"
+jetbrains-kotlin = "1.9.21"
 
 io-mockk = "1.13.8"