Downgrade firebase-messaging

use NC specific user agent for Push

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

gplay.gradle

@@ -1,3 +1,4 @@
 dependencies {
-    implementation "com.google.firebase:firebase-messaging:20.2.4"
+    // upon each update first test: new registration, receive push
+    implementation "com.google.firebase:firebase-messaging:20.1.3"
 }

src/gplay/java/com/owncloud/android/utils/PushUtils.java

@@ -242,7 +242,8 @@ public final class PushUtils {
                                     context.getResources().getString(R.string.push_server_url),
                                     token, pushResponse.getDeviceIdentifier(),
                                     pushResponse.getSignature(),
-                                    pushResponse.getPublicKey())
+                                    pushResponse.getPublicKey(),
+                                    MainApp.getUserAgent())
                                     .run();
 
                                 if (resultProxy.isSuccess()) {