Python 3.8 breakage

[jayvdb]

On Python 3.8 the test summary is

========= 6 failed, 28 passed, 1 skipped, 1 xfailed, 2 error in 1.76s ==========

All failures and errors are the same:

Example error

[   61s] ==================================== ERRORS ====================================
[   61s] ___________________ ERROR at setup of test_dependent_fixture ___________________
[   61s] tests/conftest.py:24: in dependent_fixture
[   61s]     event_loop.run_until_complete(just_a_sleep())
[   61s] /usr/lib/python3.8/asyncio/base_events.py:608: in run_until_complete
[   61s]     return future.result()
[   61s] tests/conftest.py:20: in just_a_sleep
[   61s]     await asyncio.sleep(0.1, loop=event_loop)
[   61s] /usr/lib/python3.8/asyncio/tasks.py:639: in sleep
[   61s]     warnings.warn("The loop argument is deprecated since Python 3.8, "
[   61s] E   DeprecationWarning: The loop argument is deprecated since Python 3.8, and scheduled for removal in Python 3.10.

Example failure

[   61s] ==================================== ERRORS ====================================
[   61s] ___________________ ERROR at setup of test_dependent_fixture ___________________
[   61s] tests/conftest.py:24: in dependent_fixture
[   61s]     event_loop.run_until_complete(just_a_sleep())
[   61s] /usr/lib/python3.8/asyncio/base_events.py:608: in run_until_complete
[   61s]     return future.result()
[   61s] tests/conftest.py:20: in just_a_sleep
[   61s]     await asyncio.sleep(0.1, loop=event_loop)
[   61s] /usr/lib/python3.8/asyncio/tasks.py:639: in sleep
[   61s]     warnings.warn("The loop argument is deprecated since Python 3.8, "
[   61s] E   DeprecationWarning: The loop argument is deprecated since Python 3.8, and scheduled for removal in Python 3.10.