replace init classes on python3

tests/_test_absolute.py

@@ -4,7 +4,7 @@
 import caldav
 
 
-class TestRadicale(object):
+class TestRadicale:
     SUMMARIES = set(
         (
             "Godspeed You! Black Emperor at " "Cirque Royal / Koninklijk Circus",
@@ -35,7 +35,7 @@ def test_eventslist(self):
         assert dtstart == self.DTSTART
 
 
-class TestTryton(object):
+class TestTryton:
     def setup(self):
         URL = "http://admin:admin@localhost:9080/caldav/Calendars/Test"
         self.client = caldav.DAVClient(URL)

tests/proxy.py

@@ -248,7 +248,7 @@ def handler(signo, frame):
 
 
 def daemonize(logger):
-    class DevNull(object):
+    class DevNull:
         def __init__(self):
             self.fd = os.open("/dev/null", os.O_WRONLY)
 

tests/test_caldav.py

@@ -437,7 +437,7 @@
     len(rfc6638_users) < 3,
     reason="need at least three users in rfc6638_users to be set in order to run this test",
 )
-class TestScheduling(object):
+class TestScheduling:
     """Testing support of RFC6638.
     TODO: work in progress.  Stalled a bit due to lack of proper testing accounts.  I haven't managed to get this test to pass at any systems yet, but I believe the problem is not on the library side.
     * icloud: cannot really test much with only one test account
@@ -554,7 +554,7 @@ def testInviteAndRespond(self):
     ## inbox/outbox?
 
 
-class RepeatedFunctionalTestsBaseClass(object):
+class RepeatedFunctionalTestsBaseClass:
     """This is a class with functional tests (tests that goes through
     basic functionality and actively communicates with third parties)
     that we want to repeat for all configured caldav_servers.