[lint] run `mypy on tests/test_addnodes.py` (#12111)

pyproject.toml

@@ -217,7 +217,6 @@ disallow_any_generics = false
 module = [
     # tests/
 #    "tests.conftest",
-    "tests.test_addnodes",
     "tests.test_errors",
     "tests.test_events",
     "tests.test_highlighting",

tests/test_addnodes.py

@@ -2,13 +2,18 @@
 
 from __future__ import annotations
 
+from typing import TYPE_CHECKING
+
 import pytest
 
 from sphinx import addnodes
 
+if TYPE_CHECKING:
+    from collections.abc import Generator
+
 
 @pytest.fixture()
-def sig_elements() -> set[type[addnodes.desc_sig_element]]:
+def sig_elements() -> Generator[set[type[addnodes.desc_sig_element]], None, None]:
     """Fixture returning the current ``addnodes.SIG_ELEMENTS`` set."""
     original = addnodes.SIG_ELEMENTS.copy()  # safe copy of the current nodes
     yield {*addnodes.SIG_ELEMENTS}  # temporary value to use during tests