fix(deps): update kotest

Author: renovate[bot]

gradle/libs.versions.toml

@@ -2,7 +2,7 @@
 annotation = "1.9.1"
 kotlin = "2.1.21"
 dokka = "2.0.0"
-kotest = "6.0.0.M3"
+kotest = "6.0.0.M15"
 lifecycleLivedataKtx = "2.9.1"
 lifecycleViewmodelKtx = "2.9.1"
 mavenNexus = "2.0.0"