Use package constraints in tox lint (#37500)

Otherwise fails with
pip._vendor.pkg_resources.ContextualVersionConflict: (importlib-metadata
1.7.0 (.../.tox/lint/lib/python3.7/site-packages),
Requirement.parse('importlib-metadata==1.6.0'), {'homeassistant'})

tox.ini

@@ -31,6 +31,7 @@ commands =
 [testenv:lint]
 deps =
      -r{toxinidir}/requirements_test.txt
+     -c{toxinidir}/homeassistant/package_constraints.txt
 commands =
     python -m script.gen_requirements_all validate
     python -m script.hassfest --action validate