Add better warning msg for deprecated warns(None)

src/_pytest/deprecated.py

@@ -103,7 +103,8 @@ HOOK_LEGACY_PATH_ARG = UnformattedWarning(
 )
 
 WARNS_NONE_ARG = PytestDeprecationWarning(
-    "Please pass an explicit Warning type or tuple of Warning types."
+    "Passing None to catch any warning has been deprecated, pass no arguments instead:\n"
+    " Replace pytest.warns(None) by simply pytest.warns()."
 )
 
 # You want to make some `__init__` or function "private".

testing/deprecated_test.py

@@ -183,6 +183,7 @@ def test_hookproxy_warnings_for_fspath(tmp_path, hooktype, request):
 def test_warns_none_is_deprecated():
     with pytest.warns(
         PytestDeprecationWarning,
-        match="Please pass an explicit Warning type or tuple of Warning types.",
+        match=r"Passing None to catch any warning has been deprecated, pass no arguments instead:\n Replace pytest.warns\(None\) by simply pytest.warns\(\).",
     ):
-        pytest.warns(None)
+        with pytest.warns(None):
+            pass

testing/test_recwarn.py

@@ -307,6 +307,7 @@ class TestWarns:
         assert str(record[1].message) == "runtime"
 
     def test_record_only_none_deprecated_warn(self) -> None:
+        # This should become an error when WARNS_NONE_ARG is removed in Pytest 7.0
         with warnings.catch_warnings():
             warnings.simplefilter("ignore")
             with pytest.warns(None) as record: