Fix R8 error, due to exclusion of analytics group done in #1221.

libraries/pushproviders/firebase/build.gradle.kts

@@ -20,6 +20,13 @@ plugins {
 
 android {
     namespace = "io.element.android.libraries.pushproviders.firebase"
+
+    buildTypes {
+        release {
+            isMinifyEnabled = true
+            consumerProguardFiles("consumer-proguard-rules.pro")
+        }
+    }
 }
 
 anvil {

libraries/pushproviders/firebase/consumer-proguard-rules.pro

@@ -0,0 +1,4 @@
+# Fix this error:
+# ERROR: Missing classes detected while running R8. Please add the missing classes or apply additional keep rules that are generated in /Users/bmarty/workspaces/element-x-android/app/build/outputs/mapping/nightly/missing_rules.txt.
+# ERROR: R8: Missing class com.google.firebase.analytics.connector.AnalyticsConnector (referenced from: void com.google.firebase.messaging.MessagingAnalytics.logToScion(java.lang.String, android.os.Bundle) and 1 other context)
+-dontwarn com.google.firebase.analytics.connector.AnalyticsConnector