Missing importmode with pytest 6.0.0 #118
Description
pytest 6.0.0 just came out. astropy already sees this error:
_ ERROR collecting .tox/py38-test-alldeps/lib/python3.8/site-packages/astropy/conftest.py _
../../.tox/py38-test-alldeps/lib/python3.8/site-packages/pytest_doctestplus/plugin.py:172: in collect
module = self.config.pluginmanager._importconftest(self.fspath)
E TypeError: _importconftest() missing 1 required positional argument: 'importmode'
_ ERROR collecting .tox/py38-test-alldeps/lib/python3.8/site-packages/astropy/coordinates/tests/conftest.py _
../../.tox/py38-test-alldeps/lib/python3.8/site-packages/pytest_doctestplus/plugin.py:172: in collect
module = self.config.pluginmanager._importconftest(self.fspath)
E TypeError: _importconftest() missing 1 required positional argument: 'importmode'
_ ERROR collecting .tox/py38-test-alldeps/lib/python3.8/site-packages/astropy/table/tests/conftest.py _
../../.tox/py38-test-alldeps/lib/python3.8/site-packages/pytest_doctestplus/plugin.py:172: in collect
module = self.config.pluginmanager._importconftest(self.fspath)
E TypeError: _importconftest() missing 1 required positional argument: 'importmode'
_ ERROR collecting .tox/py38-test-alldeps/lib/python3.8/site-packages/astropy/wcs/tests/conftest.py _
../../.tox/py38-test-alldeps/lib/python3.8/site-packages/pytest_doctestplus/plugin.py:172: in collect
module = self.config.pluginmanager._importconftest(self.fspath)
E TypeError: _importconftest() missing 1 required positional argument: 'importmode'
_ ERROR collecting .tox/py38-test-alldeps/lib/python3.8/site-packages/astropy/wcs/wcsapi/conftest.py _
../../.tox/py38-test-alldeps/lib/python3.8/site-packages/pytest_doctestplus/plugin.py:172: in collect
module = self.config.pluginmanager._importconftest(self.fspath)
E TypeError: _importconftest() missing 1 required positional argument: 'importmode'
______________________ ERROR collecting docs/conftest.py _______________________
../../.tox/py38-test-alldeps/lib/python3.8/site-packages/pytest_doctestplus/plugin.py:172: in collect
module = self.config.pluginmanager._importconftest(self.fspath)
E TypeError: _importconftest() missing 1 required positional argument: 'importmode'
Example log: https://travis-ci.org/github/astropy/astropy/jobs/712696735