Update dependency org.mockito:mockito-core to v5.21.0 (#65)

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

Author: renovate[bot]

android/build.gradle

@@ -59,7 +59,7 @@ android {
 
     dependencies {
         testImplementation("org.jetbrains.kotlin:kotlin-test")
-        testImplementation("org.mockito:mockito-core:5.20.0")
+        testImplementation("org.mockito:mockito-core:5.21.0")
 
         implementation 'com.android.support:appcompat-v7:28.0.0'
         implementation 'com.android.support.constraint:constraint-layout:2.0.4'