Increase visibility of Mockito dependency (#498)

To ensure Mockito is on the transitive classpath.

Author: TWiStErRob

mockito-kotlin/build.gradle

@@ -26,7 +26,7 @@ dependencies {
     compileOnly "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
     compileOnly 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.0.0'
 
-    implementation "org.mockito:mockito-core:5.7.0"
+    api "org.mockito:mockito-core:5.7.0"
 
     testImplementation 'junit:junit:4.13.2'
     testImplementation 'com.nhaarman:expect.kt:1.0.1'