Request garbage collect after operations

app/src/main/java/eu/faircode/email/ServiceSynchronize.java

@@ -1444,6 +1444,12 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
                                                                 }
                                                                 db.folder().setFolderState(folder.id, null);
                                                             }
+
+                                                            try {
+                                                                System.gc();
+                                                            } catch (Throwable ex) {
+                                                                Log.e(ex);
+                                                            }
                                                         }
                                                     } finally {
                                                         wlOperations.release();