fix several deprecation warnings

adding -Werror flag to pytest configuration
so we can flush all of those with the test we have
so we won't have user of the driver running into those
and get them fixed address as soon as we support new
python versions

cassandra/util.py

@@ -34,7 +34,7 @@
 from cassandra import DriverException
 
 DATETIME_EPOC = datetime.datetime(1970, 1, 1)
-UTC_DATETIME_EPOC = datetime.datetime.utcfromtimestamp(0)
+UTC_DATETIME_EPOC = datetime.datetime.fromtimestamp(0,  tz=datetime.timezone.utc)
 
 _nan = float('nan')
 

pytest.ini

@@ -3,3 +3,9 @@ log_format = %(asctime)s.%(msecs)03d %(levelname)s [%(module)s:%(lineno)s]: %(me
 log_level = DEBUG
 log_date_format = %Y-%m-%d %H:%M:%S
 xfail_strict=true
+
+
+addopts =
+    -Werror
+    -W'ignore::pytest.PytestCollectionWarning'
+    -W'ignore:distutils Version classes are deprecated:DeprecationWarning:eventlet.support.greenlets'