message: Make all grpc tests xfail when running on macos
  This way the CI will still fail the grpc tests don't pass
diff: +import sys
  import threading
  from concurrent import futures
  from unittest import mock
  @@ -16,6 +17,8 @@ from xain.grpc import (
  from xain.grpc.coordinator import Coordinator, Participants, monitor_heartbeats
  from xain.grpc.participant import heartbeat
  +if sys.platform == "darwin":
  + pytestmark = pytest.mark.xfail(reason="some grpc tests fail on macos")
  # pylint: disable=W0613,W0621
  @pytest.mark.integration
  @@ -53,7 +56,6 @@ def mocked_init(self, participants, required_participants=10):
  # TODO: Fix test so it also runs correctly on macos
  -@pytest.mark.xfail
  @pytest.mark.integration
  @mock.patch("xain.grpc.coordinator.Coordinator.__init__", new=mocked_init)
  def test_participant_rendezvous_later(participant_stub):
  