use same version for all org.mockito releases

Signed-off-by: tobiasKaminsky <tobias@kaminsky.me>

build.gradle

@@ -64,6 +64,7 @@ ext {
     prismVersion = "2.0.0"
     butterknifeVersion = "10.2.3"
     androidLibraryVersion = "master-SNAPSHOT"
+    mockitoVersion = "3.5.6"
 
     travisBuild = System.getenv("TRAVIS") == "true"
 
@@ -352,7 +353,7 @@ dependencies {
 
     // dependencies for local unit tests
     testImplementation 'junit:junit:4.13'
-    testImplementation 'org.mockito:mockito-core:3.4.6'
+    testImplementation "org.mockito:mockito-core:$mockitoVersion"
     testImplementation 'androidx.test:core:1.2.0'
     testImplementation 'org.powermock:powermock-core:2.0.7'
     testImplementation 'org.powermock:powermock-module-junit4:2.0.7'
@@ -379,8 +380,8 @@ dependencies {
     // Mocking support
     androidTestImplementation 'com.github.tmurakami:dexopener:2.0.5' // required to allow mocking on API 27 and older
     androidTestImplementation "com.nhaarman.mockitokotlin2:mockito-kotlin:2.2.0"
-    androidTestImplementation 'org.mockito:mockito-core:3.4.4'
-    androidTestImplementation("org.mockito:mockito-android:3.5.3") {
+    androidTestImplementation "org.mockito:mockito-core:$mockitoVersion"
+    androidTestImplementation("org.mockito:mockito-android:$mockitoVersion") {
         exclude group: "net.bytebuddy", module: "byte-buddy-android"
     }
     androidTestImplementation 'net.bytebuddy:byte-buddy:1.10.14'