Update Facebook lib version (#728)

Author: SUPERCILEX

auth/build.gradle

@@ -44,7 +44,7 @@ dependencies {
     compile "com.google.firebase:firebase-auth:$firebaseVersion"
     compile "com.google.android.gms:play-services-auth:$firebaseVersion"
 
-    compile 'com.facebook.android:facebook-android-sdk:4.22.1'
+    compile 'com.facebook.android:facebook-android-sdk:4.23.0'
     compile("com.twitter.sdk.android:twitter:2.3.2@aar") { transitive = true }
 
     // The following libraries are needed to prevent incompatibilities with the facebook

build.gradle

@@ -24,11 +24,6 @@ allprojects {
     }
 }
 
-// TODO Remove once either Facebook or Robolectric fix the crash: https://github.com/robolectric/robolectric/issues/2579#issuecomment-276526911
-gradle.taskGraph.whenReady { graph ->
-    graph.allTasks.findAll { it.name ==~ /testReleaseUnitTest/ }*.enabled = false
-}
-
 //Skip Javadoc generation for Java 1.8 as it breaks build
 if (JavaVersion.current().isJava8Compatible()) {
     allprojects {