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The coveralls checks are currently broken because the current coveralls python client at the moment is compatible only up to coverage version lower than 5.0.

Since the coverage python client already defines coverage in its dependencies, we can safely remove the coverage package from our test dependencies.

The solution for this task is to apply the following fix in all the python modules of OpenWISP: https://github.com/openwisp/django-freeradius/pull/258/files

Send a PR for each python module available in https://github.com/openwisp.