Fix whitespace in the code example

Author: bartmichu

README.md

@@ -28,14 +28,14 @@ import datetime
 server = urbackup_api.urbackup_server("http://127.0.0.1:55414/x", "admin", "foo")
 clients = server.get_status()
 diff_time = 3*24*60*60 # 3 days
-for client in clients:    
+for client in clients:
     if client["lastbackup"]=="-" or client["lastbackup"] < time.time() - diff_time:
-            
+
         if client["lastbackup"]=="-" or client["lastbackup"]==0:
             lastbackup = "Never"
         else:
             lastbackup = datetime.datetime.fromtimestamp(client["lastbackup"]).strftime("%x %X")
-                        
+
         print("Last file backup at {lastbackup} of client {clientname} is older than three days".format(
               lastbackup=lastbackup, clientname=client["name"] ) )
 ```