Fix test_root_validator_allow_reuse_same_field() for all warnings

Fix
`tests/test_validators.py::test_root_validator_allow_reuse_same_field`
to assert for both warnings emitted, including the Pydantic V1
deprecation warning.  Starting with pytest 8.0.0 (thanks to the fix for
pytest-dev/pytest#9288), `pytest.warns()` re-emits warnings that weren't
caught by the assertion, effectively causing the default run with
`-Werror` to fail.

tests/test_validators.py

@@ -2506,7 +2506,7 @@ class Model(BaseModel):
 
 
 def test_root_validator_allow_reuse_same_field():
-    with pytest.warns(UserWarning, match='`root_val` overrides an existing Pydantic `@root_validator` decorator'):
+    with pytest.warns(PydanticDeprecatedSince20), pytest.warns(UserWarning, match='`root_val` overrides an existing Pydantic `@root_validator` decorator'):
 
         class Model(BaseModel):
             x: int