Fix dep

Author: vkryachko

firebase-inappmessaging-display/firebase-inappmessaging-display.gradle

@@ -93,6 +93,7 @@ dependencies {
     testImplementation "junit:junit:4.12"
     testImplementation "org.mockito:mockito-core:2.25.0"
     testImplementation "com.google.truth:truth:1.0"
+    testImplementation 'androidx.test:core:1.2.0'
     testImplementation 'com.google.guava:guava:27.1-android'
 
     androidTestImplementation "org.mockito:mockito-core:2.25.0"