Bump kotlin from 2.1.10 to 2.1.21 (#118)

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

gradle/libs.versions.toml

@@ -1,6 +1,6 @@
 [versions]
 dokka = "2.0.0"
-kotlin = "2.1.10"
+kotlin = "2.1.21"
 kover = "0.9.1"
 knit = "0.5.0"
 spotless="7.0.3"