pytest.ini: Fix tests execution in development virtual environment
Since migration to PEP 517, executing pytest without arguments in the root directory of the graphql package triggers the following error:
ModuleNotFoundError: No module named 'swh.graphql.resolver_factory'
Explicitly setting the testpaths option in pytest.ini to swh/graphql/tests fix the issue.
See https://jenkins.softwareheritage.org/job/DENV/job/run-all-tests/1492/artifact/swh-graphql.log
Edited by Antoine Lambert