Fix attachment upload bug.

app/src/main/java/org/thoughtcrime/securesms/jobs/ResumableUploadSpecJob.java

@@ -37,6 +37,7 @@ public class ResumableUploadSpecJob extends BaseJob {
   protected void onRun() throws Exception {
     if (!FeatureFlags.attachmentsV3()) {
       Log.i(TAG, "Attachments V3 is not enabled so there is nothing to do!");
+      return;
     }
 
     ResumableUploadSpec resumableUploadSpec = ApplicationDependencies.getSignalServiceMessageSender()