PYTHON-5500 Mark test_dns_failures_logging as flaky (#2480)

Author: blink1073

test/asynchronous/test_srv_polling.py

@@ -225,6 +225,7 @@ def response_callback(*args):
 
             await self.run_scenario(response_callback, False)
 
+    @flaky(reason="PYTHON-5500")
     async def test_dns_failures_logging(self):
         from dns import exception
 

test/test_srv_polling.py

@@ -225,6 +225,7 @@ def response_callback(*args):
 
             self.run_scenario(response_callback, False)
 
+    @flaky(reason="PYTHON-5500")
     def test_dns_failures_logging(self):
         from dns import exception