azdev is broken due to pytest new version 6.1.0

When pytest upgrates from 6.0.2 to 6.1.0, azdev is broken.
https://docs.pytest.org/en/stable/changelog.html#changelog
```
Traceback (most recent call last):
File "/opt/hostedtoolcache/Python/3.8.5/x64/lib/python3.8/runpy.py", line 194, in _run_module_as_main
return _run_code(code, main_globals, None,
File "/opt/hostedtoolcache/Python/3.8.5/x64/lib/python3.8/runpy.py", line 87, in _run_code
self._inner_hookexec = lambda hook, methods, kwargs: hook.multicall(
File "/home/vsts/work/1/env/lib/python3.8/site-packages/pluggy/callers.py", line 203, in _multicall
gen.send(outcome)
File "/home/vsts/work/1/env/lib/python3.8/site-packages/_pytest/helpconfig.py", line 100, in pytest_cmdline_parse
config = outcome.get_result() # type: Config
File "/home/vsts/work/1/env/lib/python3.8/site-packages/pluggy/callers.py", line 80, in get_result
raise ex[1].with_traceback(ex[2])
File "/home/vsts/work/1/env/lib/python3.8/site-packages/pluggy/callers.py", line 187, in _multicall
res = hook_impl.function(*args)
File "/home/vsts/work/1/env/lib/python3.8/site-packages/_pytest/config/__init__.py", line 1003, in pytest_cmdline_parse
self.parse(args)
File "/home/vsts/work/1/env/lib/python3.8/site-packages/_pytest/config/__init__.py", line 1280, in parse
self._preparse(args, addopts=addopts)
File "/home/vsts/work/1/env/lib/python3.8/site-packages/_pytest/config/__init__.py", line 1172, in _preparse
self.pluginmanager.load_setuptools_entrypoints("pytest11")
File "/home/vsts/work/1/env/lib/python3.8/site-packages/pluggy/manager.py", line 299, in load_setuptools_entrypoints
plugin = ep.load()
File "/opt/hostedtoolcache/Python/3.8.5/x64/lib/python3.8/importlib/metadata.py", line 77, in load
module = import_module(match.group('module'))
File "/opt/hostedtoolcache/Python/3.8.5/x64/lib/python3.8/importlib/__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "", line 1014, in _gcd_import
File "", line 991, in _find_and_load
File "", line 975, in _find_and_load_unlocked
File "", line 671, in _load_unlocked
File "/home/vsts/work/1/env/lib/python3.8/site-packages/_pytest/assertion/rewrite.py", line 171, in exec_module
exec(co, module.__dict__)
File "/home/vsts/work/1/env/lib/python3.8/site-packages/pytest_rerunfailures.py", line 7, in
from _pytest.resultlog import ResultLog
ModuleNotFoundError: No module named '_pytest.resultlog'
```