fix(deps): update mockito monorepo to v5.21.0 (minor) (#214)

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

Author: renovate[bot]

settings.gradle.kts

@@ -43,7 +43,7 @@ dependencyResolutionManagement {
 
             // Testing dependencies
             version("junit", "6.0.1")
-            version("mockito", "5.20.0")
+            version("mockito", "5.21.0")
             version("mockbukkit", "3.133.2")
             version("assertj", "3.27.6")