Paging library went to beta

Change-Id: I836e4a849823daf4398d5a6a9febb1dc13fd93d4

Author: samtstern

firestore/build.gradle

@@ -21,8 +21,8 @@ dependencies {
     api "com.android.support:support-v4:$supportLibraryVersion"
     api "com.android.support:recyclerview-v7:$supportLibraryVersion"
     annotationProcessor "android.arch.lifecycle:compiler:$architectureVersion"
-    
-    api "android.arch.paging:runtime:1.0.0-alpha7"
+
+    api "android.arch.paging:runtime:1.0.0-beta1"
 
     androidTestImplementation 'junit:junit:4.12'
     androidTestImplementation 'com.android.support.test:runner:1.0.1'