tests: limit pytest version by <6.2.2

[efiop]

Started getting this error today. Pytest 6.2.2 was released a few hours ago.

INTERNALERROR>     self.config.hook.pytest_runtest_logreport(report=rep)
INTERNALERROR>   File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pluggy/hooks.py", line 286, in __call__
INTERNALERROR>     return self._hookexec(self, self.get_hookimpls(), kwargs)
INTERNALERROR>   File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pluggy/manager.py", line 93, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pluggy/manager.py", line 87, in <lambda>
INTERNALERROR>     firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
INTERNALERROR>   File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pluggy/callers.py", line 208, in _multicall
INTERNALERROR>     return outcome.get_result()
INTERNALERROR>   File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pluggy/callers.py", line 80, in get_result
INTERNALERROR>     raise ex[1].with_traceback(ex[2])
INTERNALERROR>   File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pluggy/callers.py", line 187, in _multicall
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pytest_tap/plugin.py", line 138, in pytest_runtest_logreport
INTERNALERROR>     reason = report.longrepr[2].split(":", 1)[1].strip()
INTERNALERROR> IndexError: list index out of range

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