Merge pull request #790 from Aiven-Open/dependabot/gradle/mockitoVersion-5.21.0

chore(deps): bump mockitoVersion from 5.20.0 to 5.21.0

Author: ivanyu

build.gradle

@@ -113,7 +113,7 @@ subprojects {
 
         junitPlatformVersion = "6.0.0"
 
-        mockitoVersion = "5.20.0"
+        mockitoVersion = "5.21.0"
 
         slf4jVersion = "1.7.36"