Another 3.10 deprecation

src/calibre/gui2/device.py

@@ -140,8 +140,7 @@ class DeviceManager(Thread):  # {{{
         '''
         :sleep_time: Time to sleep between device probes in secs
         '''
-        Thread.__init__(self)
-        self.setDaemon(True)
+        Thread.__init__(self, daemon=True)
         # [Device driver, Showing in GUI, Ejected]
         self.devices        = list(device_plugins())
         self.disabled_device_plugins = list(disabled_device_plugins())

src/calibre/library/sqlite.py

@@ -278,8 +278,7 @@ class DBThread(Thread):
     CLOSE = '-------close---------'
 
     def __init__(self, path, row_factory):
-        Thread.__init__(self)
-        self.setDaemon(True)
+        Thread.__init__(self, daemon=True)
         self.path = path
         self.unhandled_error = (None, '')
         self.row_factory = row_factory

src/calibre/utils/threadpool.py

@@ -77,9 +77,8 @@ class WorkerThread(threading.Thread):
         requestsQueue and resultQueue are instances of queue.Queue passed
         by the ThreadPool class when it creates a new worker thread.
         """
-
+        kwds['daemon'] = True
         threading.Thread.__init__(self, **kwds)
-        self.setDaemon(1)
         self.workRequestQueue = requestsQueue
         self.resultQueue = resultsQueue
         self._dismissed = threading.Event()