Disable -W error for now

We're hitting two sets of warnings in third-party code. And for some
reason, I *cannot* figure out how to filter them out right now...

tests/test_gh.py::test_basic_gh_client
tests/test_gh.py::test_client_part_of_app
  /home/njs/.user-python3.7/lib/python3.7/site-packages/anyio/_backends/_trio.py:199: TrioDeprecationWarning: trio.hazmat.wait_socket_writable is deprecated since Trio 0.12.0; use trio.hazmat.wait_writable instead (python-trio/trio#878)
    await trio.hazmat.wait_socket_writable(sock)

tests/test_gh.py::test_basic_gh_client
tests/test_gh.py::test_client_part_of_app
  /home/njs/.user-python3.7/lib/python3.7/site-packages/anyio/_backends/_trio.py:190: TrioDeprecationWarning: trio.hazmat.wait_socket_readable is deprecated since Trio 0.12.0; use trio.hazmat.wait_readable instead (python-trio/trio#878)
    await trio.hazmat.wait_socket_readable(sock)

tests/test_gh.py::test_basic_gh_client
tests/test_gh.py::test_client_part_of_app
  /home/njs/.user-python3.7/lib/python3.7/site-packages/anyio/_backends/_trio.py:179: TrioDeprecationWarning: trio.hazmat.notify_socket_close is deprecated since Trio 0.12.0; use trio.hazmat.notify_closing instead (python-trio/trio#878)
    trio.hazmat.notify_socket_close(self._raw_socket)

tests/test_gh.py::test_client_part_of_app
  /home/njs/.user-python3.7/lib/python3.7/site-packages/uritemplate/variable.py:363: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated, and in 3.8 it will stop working
    return isinstance(value, (dict, collections.MutableMapping))

ci.sh

@@ -21,6 +21,6 @@ python -m pip install -r test-requirements.txt
 
 #black --diff --check snekomatic
 
-pytest -W error -r a --verbose
+pytest -r a --verbose
 
 bash <(curl -s https://codecov.io/bash) -n "${CODECOV_NAME}"