Upgrade coverage dependency

[ofek]

Motivation

We can workaround the concurrency bug nedbat/coveragepy#883 (comment)

[codecov]

Codecov Report

Merging #5647 into master will decrease coverage by 7%.
The diff coverage is n/a.

Impacted Files	Coverage Δ
datadog_checks_dev/tests/test_docker.py	48.14% <0%> (-51.86%)	⬇️
datadog_checks_dev/tests/test__env.py	100% <0%> (ø)	⬆️
datadog_checks_dev/tests/test_structures.py	100% <0%> (ø)	⬆️
datadog_checks_dev/datadog_checks/dev/env.py	22.72% <0%> (-20.46%)	⬇️
datadog_checks_dev/tests/test_conditions.py	82.25% <0%> (-17.75%)	⬇️
datadog_checks_dev/datadog_checks/dev/docker.py	24.57% <0%> (-19.5%)	⬇️
...atadog_checks_dev/datadog_checks/dev/subprocess.py	62.16% <0%> (-16.22%)	⬇️
...checks_dev/tests/plugin/test_environment_runner.py	100% <0%> (ø)	⬆️
...atadog_checks_dev/datadog_checks/dev/structures.py	68.85% <0%> (-13.12%)	⬇️
datadog_checks_dev/datadog_checks/dev/_env.py	54.16% <0%> (-9.73%)	⬇️
... and 1005 more

[AlexandreYang]

Could you add a comment that this has been added as workaround and link to the original issue?

That will help future readers and also help clean up when the issue is resolved.