threading.Thread.setDaemon has been deprecated in favor of setting daemon attribute directly in Python 3.10

[tirkarthi]

Ref : python/cpython#25174

python -m pytest tests/test_endpoint.py::EndpointTest::test_http_server               
========================================================================= test session starts ==========================================================================
platform linux -- Python 3.10.0a7+, pytest-6.3.0.dev369+g9078c3ce2, py-1.10.0, pluggy-0.13.1
rootdir: /root/checked_repos_clone/prometheus_flask_exporter
plugins: flake8-1.0.7, virtualenv-1.7.0, shutil-1.7.0, cov-2.11.1
collected 1 item                                                                                                                                                       

tests/test_endpoint.py .                                                                                                                                         [100%]

=========================================================================== warnings summary ===========================================================================
tests/test_endpoint.py::EndpointTest::test_http_server
tests/test_endpoint.py::EndpointTest::test_http_server
tests/test_endpoint.py::EndpointTest::test_http_server
  /root/checked_repos_clone/prometheus_flask_exporter/prometheus_flask_exporter/__init__.py:304: DeprecationWarning: setDaemon() is deprecated, set the daemon attribute instead
    thread.setDaemon(True)

-- Docs: https://docs.pytest.org/en/stable/warnings.html
==================================================================== 1 passed, 3 warnings in 0.31s =====================================================================