refactor: Install & test - CPython 3.7 (ubuntu), codecov.

Author: Ajnus

tests/conftest.py

@@ -513,7 +513,7 @@ def group_dm_template() -> Message:
     return msg_template_factory(537288, "private", 1520918737, recipients=recipients)
 
 
-@pytest.fixture(params=["pm_template", "group_pm_template"])
+@pytest.fixture(params=["dm_template", "group_dm_template"])
 def private_message_fixture(request: Any) -> Message:
     return request.getfixturevalue(request.param)