Use jdk8 compatible version of mockk

Author: rubengees

gradle/versions.gradle

@@ -24,5 +24,5 @@ ext {
     junitVersion = "5.7.0"
     concurrentUnitVersion = "0.4.6"
     kluentVersion = "1.64"
-    mockkVersion = "1.10.3"
+    mockkVersion = "1.10.3-jdk8"
 }