enable the warnings plugin (#6416)

Author: graingert

pyproject.toml

@@ -4,7 +4,7 @@ src_paths = ["requests", "test"]
 honor_noqa = true
 
 [tool.pytest.ini_options]
-addopts = "-p no:warnings --doctest-modules"
+addopts = "--doctest-modules"
 doctest_optionflags = "NORMALIZE_WHITESPACE ELLIPSIS"
 minversion = "6.2"
 testpaths = [